9 files changed, 401 insertions, 1141 deletions

diff --git a/builtin/checkout.c b/builtin/checkout.c
index f1984d9933..5bf96ba4d4 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -514,20 +514,6 @@ static void report_tracking(struct branch_info *new)
 	strbuf_release(&sb);
 }
 
-static void detach_advice(const char *old_path, const char *new_name)
-{
-	const char fmt[] =
-	"Note: checking out '%s'.\n\n"
-	"You are in 'detached HEAD' state. You can look around, make experimental\n"
-	"changes and commit them, and you can discard any commits you make in this\n"
-	"state without impacting any branches by performing another checkout.\n\n"
-	"If you want to create a new branch to retain commits you create, you may\n"
-	"do so (now or later) by using -b with the checkout command again. Example:\n\n"
-	"  git checkout -b new_branch_name\n\n";
-
-	fprintf(stderr, fmt, new_name);
-}
-
 static void update_refs_for_switch(struct checkout_opts *opts,
 				   struct branch_info *old,
 				   struct branch_info *new)
@@ -575,7 +561,7 @@ static void update_refs_for_switch(struct checkout_opts *opts,
 			   REF_NODEREF, DIE_ON_ERR);
 		if (!opts->quiet) {
 			if (old->path && advice_detached_head)
-				detach_advice(old->path, new->name);
+				detach_advice(new->name);
 			describe_detached_head(_("HEAD is now at"), new->commit);
 		}
 	} else if (new->path) {	/* Switch branches. */
diff --git a/builtin/clone.c b/builtin/clone.c
index 86db954730..c62d4b5737 100644
--- a/builtin/clone.c
+++ b/builtin/clone.c
@@ -37,7 +37,7 @@ static const char * const builtin_clone_usage[] = {
 	NULL
 };
 
-static int option_no_checkout, option_bare, option_mirror;
+static int option_no_checkout, option_bare, option_mirror, option_single_branch = -1;
 static int option_local, option_no_hardlinks, option_shared, option_recursive;
 static char *option_template, *option_depth;
 static char *option_origin = NULL;
@@ -92,6 +92,8 @@ static struct option builtin_clone_options[] = {
 		   "path to git-upload-pack on the remote"),
 	OPT_STRING(0, "depth", &option_depth, "depth",
 		    "create a shallow clone of that depth"),
+	OPT_BOOL(0, "single-branch", &option_single_branch,
+		    "clone only one branch, HEAD or --branch"),
 	OPT_STRING(0, "separate-git-dir", &real_git_dir, "gitdir",
 		   "separate git dir from working tree"),
 	OPT_STRING_LIST('c', "config", &option_config, "key=value",
@@ -361,13 +363,8 @@ static void copy_or_link_directory(struct strbuf *src, struct strbuf *dest,
 	closedir(dir);
 }
 
-static const struct ref *clone_local(const char *src_repo,
-				     const char *dest_repo)
+static void clone_local(const char *src_repo, const char *dest_repo)
 {
-	const struct ref *ret;
-	struct remote *remote;
-	struct transport *transport;
-
 	if (option_shared) {
 		struct strbuf alt = STRBUF_INIT;
 		strbuf_addf(&alt, "%s/objects", src_repo);
@@ -383,13 +380,8 @@ static const struct ref *clone_local(const char *src_repo,
 		strbuf_release(&dest);
 	}
 
-	remote = remote_get(src_repo);
-	transport = transport_get(remote, src_repo);
-	ret = transport_get_remote_refs(transport);
-	transport_disconnect(transport);
 	if (0 <= option_verbosity)
 		printf(_("done.\n"));
-	return ret;
 }
 
 static const char *junk_work_tree;
@@ -420,6 +412,26 @@ static void remove_junk_on_signal(int signo)
 	raise(signo);
 }
 
+static struct ref *find_remote_branch(const struct ref *refs, const char *branch)
+{
+	struct ref *ref;
+	struct strbuf head = STRBUF_INIT;
+	strbuf_addstr(&head, "refs/heads/");
+	strbuf_addstr(&head, branch);
+	ref = find_ref_by_name(refs, head.buf);
+	strbuf_release(&head);
+
+	if (ref)
+		return ref;
+
+	strbuf_addstr(&head, "refs/tags/");
+	strbuf_addstr(&head, branch);
+	ref = find_ref_by_name(refs, head.buf);
+	strbuf_release(&head);
+
+	return ref;
+}
+
 static struct ref *wanted_peer_refs(const struct ref *refs,
 		struct refspec *refspec)
 {
@@ -427,8 +439,27 @@ static struct ref *wanted_peer_refs(const struct ref *refs,
 	struct ref *local_refs = head;
 	struct ref **tail = head ? &head->next : &local_refs;
 
-	get_fetch_map(refs, refspec, &tail, 0);
-	if (!option_mirror)
+	if (option_single_branch) {
+		struct ref *remote_head = NULL;
+
+		if (!option_branch)
+			remote_head = guess_remote_head(head, refs, 0);
+		else
+			remote_head = find_remote_branch(refs, option_branch);
+
+		if (!remote_head && option_branch)
+			warning(_("Could not find remote branch %s to clone."),
+				option_branch);
+		else {
+			get_fetch_map(remote_head, refspec, &tail, 0);
+
+			/* if --branch=tag, pull the requested tag explicitly */
+			get_fetch_map(remote_head, tag_refspec, &tail, 0);
+		}
+	} else
+		get_fetch_map(refs, refspec, &tail, 0);
+
+	if (!option_mirror && !option_single_branch)
 		get_fetch_map(refs, tag_refspec, &tail, 0);
 
 	return local_refs;
@@ -441,11 +472,135 @@ static void write_remote_refs(const struct ref *local_refs)
 	for (r = local_refs; r; r = r->next) {
 		if (!r->peer_ref)
 			continue;
-		add_extra_ref(r->peer_ref->name, r->old_sha1, 0);
+		add_packed_ref(r->peer_ref->name, r->old_sha1);
 	}
 
 	pack_refs(PACK_REFS_ALL);
-	clear_extra_refs();
+}
+
+static void write_followtags(const struct ref *refs, const char *msg)
+{
+	const struct ref *ref;
+	for (ref = refs; ref; ref = ref->next) {
+		if (prefixcmp(ref->name, "refs/tags/"))
+			continue;
+		if (!suffixcmp(ref->name, "^{}"))
+			continue;
+		if (!has_sha1_file(ref->old_sha1))
+			continue;
+		update_ref(msg, ref->name, ref->old_sha1,
+			   NULL, 0, DIE_ON_ERR);
+	}
+}
+
+static void update_remote_refs(const struct ref *refs,
+			       const struct ref *mapped_refs,
+			       const struct ref *remote_head_points_at,
+			       const char *branch_top,
+			       const char *msg)
+{
+	if (refs) {
+		clear_extra_refs();
+		write_remote_refs(mapped_refs);
+		if (option_single_branch)
+			write_followtags(refs, msg);
+	}
+
+	if (remote_head_points_at && !option_bare) {
+		struct strbuf head_ref = STRBUF_INIT;
+		strbuf_addstr(&head_ref, branch_top);
+		strbuf_addstr(&head_ref, "HEAD");
+		create_symref(head_ref.buf,
+			      remote_head_points_at->peer_ref->name,
+			      msg);
+	}
+}
+
+static void update_head(const struct ref *our, const struct ref *remote,
+			const char *msg)
+{
+	if (our && !prefixcmp(our->name, "refs/heads/")) {
+		/* Local default branch link */
+		create_symref("HEAD", our->name, NULL);
+		if (!option_bare) {
+			const char *head = skip_prefix(our->name, "refs/heads/");
+			update_ref(msg, "HEAD", our->old_sha1, NULL, 0, DIE_ON_ERR);
+			install_branch_config(0, head, option_origin, our->name);
+		}
+	} else if (our) {
+		struct commit *c = lookup_commit_reference(our->old_sha1);
+		/* --branch specifies a non-branch (i.e. tags), detach HEAD */
+		update_ref(msg, "HEAD", c->object.sha1,
+			   NULL, REF_NODEREF, DIE_ON_ERR);
+	} else if (remote) {
+		/*
+		 * We know remote HEAD points to a non-branch, or
+		 * HEAD points to a branch but we don't know which one.
+		 * Detach HEAD in all these cases.
+		 */
+		update_ref(msg, "HEAD", remote->old_sha1,
+			   NULL, REF_NODEREF, DIE_ON_ERR);
+	}
+}
+
+static int checkout(void)
+{
+	unsigned char sha1[20];
+	char *head;
+	struct lock_file *lock_file;
+	struct unpack_trees_options opts;
+	struct tree *tree;
+	struct tree_desc t;
+	int err = 0, fd;
+
+	if (option_no_checkout)
+		return 0;
+
+	head = resolve_refdup("HEAD", sha1, 1, NULL);
+	if (!head) {
+		warning(_("remote HEAD refers to nonexistent ref, "
+			  "unable to checkout.\n"));
+		return 0;
+	}
+	if (!strcmp(head, "HEAD")) {
+		if (advice_detached_head)
+			detach_advice(sha1_to_hex(sha1));
+	} else {
+		if (prefixcmp(head, "refs/heads/"))
+			die(_("HEAD not found below refs/heads!"));
+	}
+	free(head);
+
+	/* We need to be in the new work tree for the checkout */
+	setup_work_tree();
+
+	lock_file = xcalloc(1, sizeof(struct lock_file));
+	fd = hold_locked_index(lock_file, 1);
+
+	memset(&opts, 0, sizeof opts);
+	opts.update = 1;
+	opts.merge = 1;
+	opts.fn = oneway_merge;
+	opts.verbose_update = (option_verbosity > 0);
+	opts.src_index = &the_index;
+	opts.dst_index = &the_index;
+
+	tree = parse_tree_indirect(sha1);
+	parse_tree(tree);
+	init_tree_desc(&t, tree->buffer, tree->size);
+	unpack_trees(1, &t, &opts);
+
+	if (write_cache(fd, active_cache, active_nr) ||
+	    commit_locked_index(lock_file))
+		die(_("unable to write new index file"));
+
+	err |= run_hook(NULL, "post-checkout", sha1_to_hex(null_sha1),
+			sha1_to_hex(sha1), "1", NULL);
+
+	if (!err && option_recursive)
+		err = run_command_v_opt(argv_submodule, RUN_GIT_CMD);
+
+	return err;
 }
 
 static int write_one_config(const char *key, const char *value, void *data)
@@ -475,11 +630,13 @@ int cmd_clone(int argc, const char **argv, const char *prefix)
 	const struct ref *remote_head_points_at;
 	const struct ref *our_head_points_at;
 	struct ref *mapped_refs;
+	const struct ref *ref;
 	struct strbuf key = STRBUF_INIT, value = STRBUF_INIT;
 	struct strbuf branch_top = STRBUF_INIT, reflog_msg = STRBUF_INIT;
 	struct transport *transport = NULL;
-	char *src_ref_prefix = "refs/heads/";
-	int err = 0;
+	const char *src_ref_prefix = "refs/heads/";
+	struct remote *remote;
+	int err = 0, complete_refs_before_fetch = 1;
 
 	struct refspec *refspec;
 	const char *fetch_pattern;
@@ -498,6 +655,9 @@ int cmd_clone(int argc, const char **argv, const char *prefix)
 		usage_msg_opt(_("You must specify a repository to clone."),
 			builtin_clone_usage, builtin_clone_options);
 
+	if (option_single_branch == -1)
+		option_single_branch = option_depth ? 1 : 0;
+
 	if (option_mirror)
 		option_bare = 1;
 
@@ -630,13 +790,10 @@ int cmd_clone(int argc, const char **argv, const char *prefix)
 
 	strbuf_reset(&value);
 
-	if (is_local) {
-		refs = clone_local(path, git_dir);
-		mapped_refs = wanted_peer_refs(refs, refspec);
-	} else {
-		struct remote *remote = remote_get(option_origin);
-		transport = transport_get(remote, remote->url[0]);
+	remote = remote_get(option_origin);
+	transport = transport_get(remote, remote->url[0]);
 
+	if (!is_local) {
 		if (!transport->get_refs_list || !transport->fetch)
 			die(_("Don't know how to clone %s"), transport->url);
 
@@ -645,43 +802,50 @@ int cmd_clone(int argc, const char **argv, const char *prefix)
 		if (option_depth)
 			transport_set_option(transport, TRANS_OPT_DEPTH,
 					     option_depth);
+		if (option_single_branch)
+			transport_set_option(transport, TRANS_OPT_FOLLOWTAGS, "1");
 
 		transport_set_verbosity(transport, option_verbosity, option_progress);
 
 		if (option_upload_pack)
 			transport_set_option(transport, TRANS_OPT_UPLOADPACK,
 					     option_upload_pack);
-
-		refs = transport_get_remote_refs(transport);
-		if (refs) {
-			mapped_refs = wanted_peer_refs(refs, refspec);
-			transport_fetch_refs(transport, mapped_refs);
-		}
 	}
 
-	if (refs) {
-		clear_extra_refs();
+	refs = transport_get_remote_refs(transport);
+	mapped_refs = refs ? wanted_peer_refs(refs, refspec) : NULL;
 
-		write_remote_refs(mapped_refs);
+	/*
+	 * transport_get_remote_refs() may return refs with null sha-1
+	 * in mapped_refs (see struct transport->get_refs_list
+	 * comment). In that case we need fetch it early because
+	 * remote_head code below relies on it.
+	 *
+	 * for normal clones, transport_get_remote_refs() should
+	 * return reliable ref set, we can delay cloning until after
+	 * remote HEAD check.
+	 */
+	for (ref = refs; ref; ref = ref->next)
+		if (is_null_sha1(ref->old_sha1)) {
+			complete_refs_before_fetch = 0;
+			break;
+		}
 
+	if (!is_local && !complete_refs_before_fetch && refs)
+		transport_fetch_refs(transport, mapped_refs);
+
+	if (refs) {
 		remote_head = find_ref_by_name(refs, "HEAD");
 		remote_head_points_at =
 			guess_remote_head(remote_head, mapped_refs, 0);
 
 		if (option_branch) {
-			struct strbuf head = STRBUF_INIT;
-			strbuf_addstr(&head, src_ref_prefix);
-			strbuf_addstr(&head, option_branch);
 			our_head_points_at =
-				find_ref_by_name(mapped_refs, head.buf);
-			strbuf_release(&head);
-
-			if (!our_head_points_at) {
-				warning(_("Remote branch %s not found in "
-					"upstream %s, using HEAD instead"),
-					option_branch, option_origin);
-				our_head_points_at = remote_head_points_at;
-			}
+				find_remote_branch(mapped_refs, option_branch);
+
+			if (!our_head_points_at)
+				die(_("Remote branch %s not found in upstream %s"),
+				    option_branch, option_origin);
 		}
 		else
 			our_head_points_at = remote_head_points_at;
@@ -697,84 +861,20 @@ int cmd_clone(int argc, const char **argv, const char *prefix)
 					      "refs/heads/master");
 	}
 
-	if (remote_head_points_at && !option_bare) {
-		struct strbuf head_ref = STRBUF_INIT;
-		strbuf_addstr(&head_ref, branch_top.buf);
-		strbuf_addstr(&head_ref, "HEAD");
-		create_symref(head_ref.buf,
-			      remote_head_points_at->peer_ref->name,
-			      reflog_msg.buf);
-	}
+	if (is_local)
+		clone_local(path, git_dir);
+	else if (refs && complete_refs_before_fetch)
+		transport_fetch_refs(transport, mapped_refs);
 
-	if (our_head_points_at) {
-		/* Local default branch link */
-		create_symref("HEAD", our_head_points_at->name, NULL);
-		if (!option_bare) {
-			const char *head = skip_prefix(our_head_points_at->name,
-						       "refs/heads/");
-			update_ref(reflog_msg.buf, "HEAD",
-				   our_head_points_at->old_sha1,
-				   NULL, 0, DIE_ON_ERR);
-			install_branch_config(0, head, option_origin,
-					      our_head_points_at->name);
-		}
-	} else if (remote_head) {
-		/* Source had detached HEAD pointing somewhere. */
-		if (!option_bare) {
-			update_ref(reflog_msg.buf, "HEAD",
-				   remote_head->old_sha1,
-				   NULL, REF_NODEREF, DIE_ON_ERR);
-			our_head_points_at = remote_head;
-		}
-	} else {
-		/* Nothing to checkout out */
-		if (!option_no_checkout)
-			warning(_("remote HEAD refers to nonexistent ref, "
-				"unable to checkout.\n"));
-		option_no_checkout = 1;
-	}
+	update_remote_refs(refs, mapped_refs, remote_head_points_at,
+			   branch_top.buf, reflog_msg.buf);
 
-	if (transport) {
-		transport_unlock_pack(transport);
-		transport_disconnect(transport);
-	}
+	update_head(our_head_points_at, remote_head, reflog_msg.buf);
 
-	if (!option_no_checkout) {
-		struct lock_file *lock_file = xcalloc(1, sizeof(struct lock_file));
-		struct unpack_trees_options opts;
-		struct tree *tree;
-		struct tree_desc t;
-		int fd;
-
-		/* We need to be in the new work tree for the checkout */
-		setup_work_tree();
-
-		fd = hold_locked_index(lock_file, 1);
-
-		memset(&opts, 0, sizeof opts);
-		opts.update = 1;
-		opts.merge = 1;
-		opts.fn = oneway_merge;
-		opts.verbose_update = (option_verbosity > 0);
-		opts.src_index = &the_index;
-		opts.dst_index = &the_index;
-
-		tree = parse_tree_indirect(our_head_points_at->old_sha1);
-		parse_tree(tree);
-		init_tree_desc(&t, tree->buffer, tree->size);
-		unpack_trees(1, &t, &opts);
-
-		if (write_cache(fd, active_cache, active_nr) ||
-		    commit_locked_index(lock_file))
-			die(_("unable to write new index file"));
-
-		err |= run_hook(NULL, "post-checkout", sha1_to_hex(null_sha1),
-				sha1_to_hex(our_head_points_at->old_sha1), "1",
-				NULL);
-
-		if (!err && option_recursive)
-			err = run_command_v_opt(argv_submodule, RUN_GIT_CMD);
-	}
+	transport_unlock_pack(transport);
+	transport_disconnect(transport);
+
+	err = checkout();
 
 	strbuf_release(&reflog_msg);
 	strbuf_release(&branch_top);
diff --git a/builtin/fetch.c b/builtin/fetch.c
index 0481c169ca..ab186332fa 100644
--- a/builtin/fetch.c
+++ b/builtin/fetch.c
@@ -585,7 +585,7 @@ static void find_non_local_tags(struct transport *transport,
 
 	for_each_ref(add_existing, &existing_refs);
 	for (ref = transport_get_remote_refs(transport); ref; ref = ref->next) {
-		if (prefixcmp(ref->name, "refs/tags"))
+		if (prefixcmp(ref->name, "refs/tags/"))
 			continue;
 
 		/*
diff --git a/builtin/grep.c b/builtin/grep.c
index 9ce064ac11..5c2ae94e55 100644
--- a/builtin/grep.c
+++ b/builtin/grep.c
@@ -1034,8 +1034,9 @@ int cmd_grep(int argc, const char **argv, const char *prefix)
 
 #ifndef NO_PTHREADS
 	if (use_threads) {
-		if (opt.pre_context || opt.post_context || opt.file_break ||
-		    opt.funcbody)
+		if (!(opt.name_only || opt.unmatch_name_only || opt.count)
+		    && (opt.pre_context || opt.post_context ||
+			opt.file_break || opt.funcbody))
 			skip_first_line = 1;
 		start_threads(&opt);
 	}
diff --git a/builtin/index-pack.c b/builtin/index-pack.c
index af7dc37a44..dd1c5c961d 100644
--- a/builtin/index-pack.c
+++ b/builtin/index-pack.c
@@ -34,6 +34,8 @@ struct base_data {
 	struct object_entry *obj;
 	void *data;
 	unsigned long size;
+	int ref_first, ref_last;
+	int ofs_first, ofs_last;
 };
 
 /*
@@ -221,6 +223,15 @@ static NORETURN void bad_object(unsigned long offset, const char *format, ...)
 	die("pack has bad object at offset %lu: %s", offset, buf);
 }
 
+static struct base_data *alloc_base_data(void)
+{
+	struct base_data *base = xmalloc(sizeof(struct base_data));
+	memset(base, 0, sizeof(*base));
+	base->ref_last = -1;
+	base->ofs_last = -1;
+	return base;
+}
+
 static void free_base_data(struct base_data *c)
 {
 	if (c->data) {
@@ -504,14 +515,52 @@ static int is_delta_type(enum object_type type)
 	return (type == OBJ_REF_DELTA || type == OBJ_OFS_DELTA);
 }
 
+/*
+ * This function is part of find_unresolved_deltas(). There are two
+ * walkers going in the opposite ways.
+ *
+ * The first one in find_unresolved_deltas() traverses down from
+ * parent node to children, deflating nodes along the way. However,
+ * memory for deflated nodes is limited by delta_base_cache_limit, so
+ * at some point parent node's deflated content may be freed.
+ *
+ * The second walker is this function, which goes from current node up
+ * to top parent if necessary to deflate the node. In normal
+ * situation, its parent node would be already deflated, so it just
+ * needs to apply delta.
+ *
+ * In the worst case scenario, parent node is no longer deflated because
+ * we're running out of delta_base_cache_limit; we need to re-deflate
+ * parents, possibly up to the top base.
+ *
+ * All deflated objects here are subject to be freed if we exceed
+ * delta_base_cache_limit, just like in find_unresolved_deltas(), we
+ * just need to make sure the last node is not freed.
+ */
 static void *get_base_data(struct base_data *c)
 {
 	if (!c->data) {
 		struct object_entry *obj = c->obj;
+		struct base_data **delta = NULL;
+		int delta_nr = 0, delta_alloc = 0;
 
-		if (is_delta_type(obj->type)) {
-			void *base = get_base_data(c->base);
-			void *raw = get_data_from_pack(obj);
+		while (is_delta_type(c->obj->type) && !c->data) {
+			ALLOC_GROW(delta, delta_nr + 1, delta_alloc);
+			delta[delta_nr++] = c;
+			c = c->base;
+		}
+		if (!delta_nr) {
+			c->data = get_data_from_pack(obj);
+			c->size = obj->size;
+			base_cache_used += c->size;
+			prune_base_data(c);
+		}
+		for (; delta_nr > 0; delta_nr--) {
+			void *base, *raw;
+			c = delta[delta_nr - 1];
+			obj = c->obj;
+			base = get_base_data(c->base);
+			raw = get_data_from_pack(obj);
 			c->data = patch_delta(
 				base, c->base->size,
 				raw, obj->size,
@@ -519,13 +568,10 @@ static void *get_base_data(struct base_data *c)
 			free(raw);
 			if (!c->data)
 				bad_object(obj->idx.offset, "failed to apply delta");
-		} else {
-			c->data = get_data_from_pack(obj);
-			c->size = obj->size;
+			base_cache_used += c->size;
+			prune_base_data(c);
 		}
-
-		base_cache_used += c->size;
-		prune_base_data(c);
+		free(delta);
 	}
 	return c->data;
 }
@@ -553,58 +599,76 @@ static void resolve_delta(struct object_entry *delta_obj,
 	nr_resolved_deltas++;
 }
 
-static void find_unresolved_deltas(struct base_data *base,
-				   struct base_data *prev_base)
+static struct base_data *find_unresolved_deltas_1(struct base_data *base,
+						  struct base_data *prev_base)
 {
-	int i, ref_first, ref_last, ofs_first, ofs_last;
-
-	/*
-	 * This is a recursive function. Those brackets should help reducing
-	 * stack usage by limiting the scope of the delta_base union.
-	 */
-	{
+	if (base->ref_last == -1 && base->ofs_last == -1) {
 		union delta_base base_spec;
 
 		hashcpy(base_spec.sha1, base->obj->idx.sha1);
 		find_delta_children(&base_spec,
-				    &ref_first, &ref_last, OBJ_REF_DELTA);
+				    &base->ref_first, &base->ref_last, OBJ_REF_DELTA);
 
 		memset(&base_spec, 0, sizeof(base_spec));
 		base_spec.offset = base->obj->idx.offset;
 		find_delta_children(&base_spec,
-				    &ofs_first, &ofs_last, OBJ_OFS_DELTA);
-	}
+				    &base->ofs_first, &base->ofs_last, OBJ_OFS_DELTA);
 
-	if (ref_last == -1 && ofs_last == -1) {
-		free(base->data);
-		return;
-	}
+		if (base->ref_last == -1 && base->ofs_last == -1) {
+			free(base->data);
+			return NULL;
+		}
 
-	link_base_data(prev_base, base);
+		link_base_data(prev_base, base);
+	}
 
-	for (i = ref_first; i <= ref_last; i++) {
-		struct object_entry *child = objects + deltas[i].obj_no;
-		struct base_data result;
+	if (base->ref_first <= base->ref_last) {
+		struct object_entry *child = objects + deltas[base->ref_first].obj_no;
+		struct base_data *result = alloc_base_data();
 
 		assert(child->real_type == OBJ_REF_DELTA);
-		resolve_delta(child, base, &result);
-		if (i == ref_last && ofs_last == -1)
+		resolve_delta(child, base, result);
+		if (base->ref_first == base->ref_last && base->ofs_last == -1)
 			free_base_data(base);
-		find_unresolved_deltas(&result, base);
+
+		base->ref_first++;
+		return result;
 	}
 
-	for (i = ofs_first; i <= ofs_last; i++) {
-		struct object_entry *child = objects + deltas[i].obj_no;
-		struct base_data result;
+	if (base->ofs_first <= base->ofs_last) {
+		struct object_entry *child = objects + deltas[base->ofs_first].obj_no;
+		struct base_data *result = alloc_base_data();
 
 		assert(child->real_type == OBJ_OFS_DELTA);
-		resolve_delta(child, base, &result);
-		if (i == ofs_last)
+		resolve_delta(child, base, result);
+		if (base->ofs_first == base->ofs_last)
 			free_base_data(base);
-		find_unresolved_deltas(&result, base);
+
+		base->ofs_first++;
+		return result;
 	}
 
 	unlink_base_data(base);
+	return NULL;
+}
+
+static void find_unresolved_deltas(struct base_data *base)
+{
+	struct base_data *new_base, *prev_base = NULL;
+	for (;;) {
+		new_base = find_unresolved_deltas_1(base, prev_base);
+
+		if (new_base) {
+			prev_base = base;
+			base = new_base;
+		} else {
+			free(base);
+			base = prev_base;
+			if (!base)
+				return;
+			prev_base = base->base;
+		}
+	}
 }
 
 static int compare_delta_entry(const void *a, const void *b)
@@ -684,13 +748,13 @@ static void parse_pack_objects(unsigned char *sha1)
 		progress = start_progress("Resolving deltas", nr_deltas);
 	for (i = 0; i < nr_objects; i++) {
 		struct object_entry *obj = &objects[i];
-		struct base_data base_obj;
+		struct base_data *base_obj = alloc_base_data();
 
 		if (is_delta_type(obj->type))
 			continue;
-		base_obj.obj = obj;
-		base_obj.data = NULL;
-		find_unresolved_deltas(&base_obj, NULL);
+		base_obj->obj = obj;
+		base_obj->data = NULL;
+		find_unresolved_deltas(base_obj);
 		display_progress(progress, nr_resolved_deltas);
 	}
 }
@@ -783,20 +847,20 @@ static void fix_unresolved_deltas(struct sha1file *f, int nr_unresolved)
 	for (i = 0; i < n; i++) {
 		struct delta_entry *d = sorted_by_pos[i];
 		enum object_type type;
-		struct base_data base_obj;
+		struct base_data *base_obj = alloc_base_data();
 
 		if (objects[d->obj_no].real_type != OBJ_REF_DELTA)
 			continue;
-		base_obj.data = read_sha1_file(d->base.sha1, &type, &base_obj.size);
-		if (!base_obj.data)
+		base_obj->data = read_sha1_file(d->base.sha1, &type, &base_obj->size);
+		if (!base_obj->data)
 			continue;
 
-		if (check_sha1_signature(d->base.sha1, base_obj.data,
-				base_obj.size, typename(type)))
+		if (check_sha1_signature(d->base.sha1, base_obj->data,
+				base_obj->size, typename(type)))
 			die("local object %s is corrupt", sha1_to_hex(d->base.sha1));
-		base_obj.obj = append_obj_to_pack(f, d->base.sha1,
-					base_obj.data, base_obj.size, type);
-		find_unresolved_deltas(&base_obj, NULL);
+		base_obj->obj = append_obj_to_pack(f, d->base.sha1,
+					base_obj->data, base_obj->size, type);
+		find_unresolved_deltas(base_obj);
 		display_progress(progress, nr_resolved_deltas);
 	}
 	free(sorted_by_pos);
diff --git a/builtin/mailinfo.c b/builtin/mailinfo.c
index bfb32b7233..eaf9e157a3 100644
--- a/builtin/mailinfo.c
+++ b/builtin/mailinfo.c
@@ -250,8 +250,17 @@ static void cleanup_subject(struct strbuf *subject)
 			    (7 <= remove &&
 			     memmem(subject->buf + at, remove, "PATCH", 5)))
 				strbuf_remove(subject, at, remove);
-			else
+			else {
 				at += remove;
+				/*
+				 * If the input had a space after the ], keep
+				 * it.  We don't bother with finding the end of
+				 * the space, since we later normalize it
+				 * anyway.
+				 */
+				if (isspace(subject->buf[at]))
+					at += 1;
+			}
 			continue;
 		}
 		break;
diff --git a/builtin/merge.c b/builtin/merge.c
index 3a451727d0..62c7b68177 100644
--- a/builtin/merge.c
+++ b/builtin/merge.c
@@ -48,7 +48,7 @@ static const char * const builtin_merge_usage[] = {
 
 static int show_diffstat = 1, shortlog_len = -1, squash;
 static int option_commit = 1, allow_fast_forward = 1;
-static int fast_forward_only, option_edit;
+static int fast_forward_only, option_edit = -1;
 static int allow_trivial = 1, have_message;
 static int overwrite_ignore = 1;
 static struct strbuf merge_msg = STRBUF_INIT;
@@ -193,7 +193,7 @@ static struct option builtin_merge_options[] = {
 		"create a single commit instead of doing a merge"),
 	OPT_BOOLEAN(0, "commit", &option_commit,
 		"perform a commit if the merge succeeds (default)"),
-	OPT_BOOLEAN('e', "edit", &option_edit,
+	OPT_BOOL('e', "edit", &option_edit,
 		"edit message before committing"),
 	OPT_BOOLEAN(0, "ff", &allow_fast_forward,
 		"allow fast-forward (default)"),
@@ -885,20 +885,30 @@ static void abort_commit(const char *err_msg)
 	exit(1);
 }
 
+static const char merge_editor_comment[] =
+N_("Please enter a commit message to explain why this merge is necessary,\n"
+   "especially if it merges an updated upstream into a topic branch.\n"
+   "\n"
+   "Lines starting with '#' will be ignored, and an empty message aborts\n"
+   "the commit.\n");
+
 static void prepare_to_commit(void)
 {
 	struct strbuf msg = STRBUF_INIT;
+	const char *comment = _(merge_editor_comment);
 	strbuf_addbuf(&msg, &merge_msg);
 	strbuf_addch(&msg, '\n');
+	if (0 < option_edit)
+		strbuf_add_lines(&msg, "# ", comment, strlen(comment));
 	write_merge_msg(&msg);
 	run_hook(get_index_file(), "prepare-commit-msg",
 		 git_path("MERGE_MSG"), "merge", NULL, NULL);
-	if (option_edit) {
+	if (0 < option_edit) {
 		if (launch_editor(git_path("MERGE_MSG"), NULL, NULL))
 			abort_commit(NULL);
 	}
 	read_merge_msg(&msg);
-	stripspace(&msg, option_edit);
+	stripspace(&msg, 0 < option_edit);
 	if (!msg.len)
 		abort_commit(_("Empty commit message."));
 	strbuf_release(&merge_msg);
@@ -1099,6 +1109,33 @@ static void write_merge_state(void)
 	close(fd);
 }
 
+static int default_edit_option(void)
+{
+	static const char name[] = "GIT_MERGE_AUTOEDIT";
+	const char *e = getenv(name);
+	struct stat st_stdin, st_stdout;
+
+	if (have_message)
+		/* an explicit -m msg without --[no-]edit */
+		return 0;
+
+	if (e) {
+		int v = git_config_maybe_bool(name, e);
+		if (v < 0)
+			die("Bad value '%s' in environment '%s'", e, name);
+		return v;
+	}
+
+	/* Use editor if stdin and stdout are the same and is a tty */
+	return (!fstat(0, &st_stdin) &&
+		!fstat(1, &st_stdout) &&
+		isatty(0) &&
+		st_stdin.st_dev == st_stdout.st_dev &&
+		st_stdin.st_ino == st_stdout.st_ino &&
+		st_stdin.st_mode == st_stdout.st_mode);
+}
+
+
 int cmd_merge(int argc, const char **argv, const char *prefix)
 {
 	unsigned char result_tree[20];
@@ -1291,6 +1328,9 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
 		}
 	}
 
+	if (option_edit < 0)
+		option_edit = default_edit_option();
+
 	if (!use_strategies) {
 		if (!remoteheads->next)
 			add_strategies(pull_twohead, DEFAULT_TWOHEAD);
diff --git a/builtin/remote.c b/builtin/remote.c
index 583eec90e0..f54a89adc7 100644
--- a/builtin/remote.c
+++ b/builtin/remote.c
@@ -534,7 +534,7 @@ static int add_branch_for_removal(const char *refname,
 	}
 
 	/* don't delete non-remote-tracking refs */
-	if (prefixcmp(refname, "refs/remotes")) {
+	if (prefixcmp(refname, "refs/remotes/")) {
 		/* advise user how to delete local branches */
 		if (!prefixcmp(refname, "refs/heads/"))
 			string_list_append(branches->skipped,
diff --git a/builtin/revert.c b/builtin/revert.c
index 0d8020cf64..e6840f23dc 100644
--- a/builtin/revert.c
+++ b/builtin/revert.c
@@ -1,18 +1,9 @@
 #include "cache.h"
 #include "builtin.h"
-#include "object.h"
-#include "commit.h"
-#include "tag.h"
-#include "run-command.h"
-#include "exec_cmd.h"
-#include "utf8.h"
 #include "parse-options.h"
-#include "cache-tree.h"
 #include "diff.h"
 #include "revision.h"
 #include "rerere.h"
-#include "merge-recursive.h"
-#include "refs.h"
 #include "dir.h"
 #include "sequencer.h"
 
@@ -39,49 +30,14 @@ static const char * const cherry_pick_usage[] = {
 	NULL
 };
 
-enum replay_action { REVERT, CHERRY_PICK };
-enum replay_subcommand {
-	REPLAY_NONE,
-	REPLAY_REMOVE_STATE,
-	REPLAY_CONTINUE,
-	REPLAY_ROLLBACK
-};
-
-struct replay_opts {
-	enum replay_action action;
-	enum replay_subcommand subcommand;
-
-	/* Boolean options */
-	int edit;
-	int record_origin;
-	int no_commit;
-	int signoff;
-	int allow_ff;
-	int allow_rerere_auto;
-
-	int mainline;
-
-	/* Merge strategy */
-	const char *strategy;
-	const char **xopts;
-	size_t xopts_nr, xopts_alloc;
-
-	/* Only used by REPLAY_NONE */
-	struct rev_info *revs;
-};
-
-#define GIT_REFLOG_ACTION "GIT_REFLOG_ACTION"
-
 static const char *action_name(const struct replay_opts *opts)
 {
-	return opts->action == REVERT ? "revert" : "cherry-pick";
+	return opts->action == REPLAY_REVERT ? "revert" : "cherry-pick";
 }
 
-static char *get_encoding(const char *message);
-
 static const char * const *revert_or_cherry_pick_usage(struct replay_opts *opts)
 {
-	return opts->action == REVERT ? revert_usage : cherry_pick_usage;
+	return opts->action == REPLAY_REVERT ? revert_usage : cherry_pick_usage;
 }
 
 static int option_parse_x(const struct option *opt,
@@ -160,7 +116,7 @@ static void parse_args(int argc, const char **argv, struct replay_opts *opts)
 		OPT_END(),
 	};
 
-	if (opts->action == CHERRY_PICK) {
+	if (opts->action == REPLAY_PICK) {
 		struct option cp_extra[] = {
 			OPT_BOOLEAN('x', NULL, &opts->record_origin, "append commit name"),
 			OPT_BOOLEAN(0, "ff", &opts->allow_ff, "allow fast-forward"),
@@ -237,902 +193,6 @@ static void parse_args(int argc, const char **argv, struct replay_opts *opts)
 		usage_with_options(usage_str, options);
 }
 
-struct commit_message {
-	char *parent_label;
-	const char *label;
-	const char *subject;
-	char *reencoded_message;
-	const char *message;
-};
-
-static int get_message(struct commit *commit, struct commit_message *out)
-{
-	const char *encoding;
-	const char *abbrev, *subject;
-	int abbrev_len, subject_len;
-	char *q;
-
-	if (!commit->buffer)
-		return -1;
-	encoding = get_encoding(commit->buffer);
-	if (!encoding)
-		encoding = "UTF-8";
-	if (!git_commit_encoding)
-		git_commit_encoding = "UTF-8";
-
-	out->reencoded_message = NULL;
-	out->message = commit->buffer;
-	if (strcmp(encoding, git_commit_encoding))
-		out->reencoded_message = reencode_string(commit->buffer,
-					git_commit_encoding, encoding);
-	if (out->reencoded_message)
-		out->message = out->reencoded_message;
-
-	abbrev = find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV);
-	abbrev_len = strlen(abbrev);
-
-	subject_len = find_commit_subject(out->message, &subject);
-
-	out->parent_label = xmalloc(strlen("parent of ") + abbrev_len +
-			      strlen("... ") + subject_len + 1);
-	q = out->parent_label;
-	q = mempcpy(q, "parent of ", strlen("parent of "));
-	out->label = q;
-	q = mempcpy(q, abbrev, abbrev_len);
-	q = mempcpy(q, "... ", strlen("... "));
-	out->subject = q;
-	q = mempcpy(q, subject, subject_len);
-	*q = '\0';
-	return 0;
-}
-
-static void free_message(struct commit_message *msg)
-{
-	free(msg->parent_label);
-	free(msg->reencoded_message);
-}
-
-static char *get_encoding(const char *message)
-{
-	const char *p = message, *eol;
-
-	while (*p && *p != '\n') {
-		for (eol = p + 1; *eol && *eol != '\n'; eol++)
-			; /* do nothing */
-		if (!prefixcmp(p, "encoding ")) {
-			char *result = xmalloc(eol - 8 - p);
-			strlcpy(result, p + 9, eol - 8 - p);
-			return result;
-		}
-		p = eol;
-		if (*p == '\n')
-			p++;
-	}
-	return NULL;
-}
-
-static void write_cherry_pick_head(struct commit *commit, const char *pseudoref)
-{
-	const char *filename;
-	int fd;
-	struct strbuf buf = STRBUF_INIT;
-
-	strbuf_addf(&buf, "%s\n", sha1_to_hex(commit->object.sha1));
-
-	filename = git_path("%s", pseudoref);
-	fd = open(filename, O_WRONLY | O_CREAT, 0666);
-	if (fd < 0)
-		die_errno(_("Could not open '%s' for writing"), filename);
-	if (write_in_full(fd, buf.buf, buf.len) != buf.len || close(fd))
-		die_errno(_("Could not write to '%s'"), filename);
-	strbuf_release(&buf);
-}
-
-static void print_advice(int show_hint)
-{
-	char *msg = getenv("GIT_CHERRY_PICK_HELP");
-
-	if (msg) {
-		fprintf(stderr, "%s\n", msg);
-		/*
-		 * A conflict has occured but the porcelain
-		 * (typically rebase --interactive) wants to take care
-		 * of the commit itself so remove CHERRY_PICK_HEAD
-		 */
-		unlink(git_path("CHERRY_PICK_HEAD"));
-		return;
-	}
-
-	if (show_hint) {
-		advise("after resolving the conflicts, mark the corrected paths");
-		advise("with 'git add <paths>' or 'git rm <paths>'");
-		advise("and commit the result with 'git commit'");
-	}
-}
-
-static void write_message(struct strbuf *msgbuf, const char *filename)
-{
-	static struct lock_file msg_file;
-
-	int msg_fd = hold_lock_file_for_update(&msg_file, filename,
-					       LOCK_DIE_ON_ERROR);
-	if (write_in_full(msg_fd, msgbuf->buf, msgbuf->len) < 0)
-		die_errno(_("Could not write to %s"), filename);
-	strbuf_release(msgbuf);
-	if (commit_lock_file(&msg_file) < 0)
-		die(_("Error wrapping up %s"), filename);
-}
-
-static struct tree *empty_tree(void)
-{
-	return lookup_tree((const unsigned char *)EMPTY_TREE_SHA1_BIN);
-}
-
-static int error_dirty_index(struct replay_opts *opts)
-{
-	if (read_cache_unmerged())
-		return error_resolve_conflict(action_name(opts));
-
-	/* Different translation strings for cherry-pick and revert */
-	if (opts->action == CHERRY_PICK)
-		error(_("Your local changes would be overwritten by cherry-pick."));
-	else
-		error(_("Your local changes would be overwritten by revert."));
-
-	if (advice_commit_before_merge)
-		advise(_("Commit your changes or stash them to proceed."));
-	return -1;
-}
-
-static int fast_forward_to(const unsigned char *to, const unsigned char *from)
-{
-	struct ref_lock *ref_lock;
-
-	read_cache();
-	if (checkout_fast_forward(from, to))
-		exit(1); /* the callee should have complained already */
-	ref_lock = lock_any_ref_for_update("HEAD", from, 0);
-	return write_ref_sha1(ref_lock, to, "cherry-pick");
-}
-
-static int do_recursive_merge(struct commit *base, struct commit *next,
-			      const char *base_label, const char *next_label,
-			      unsigned char *head, struct strbuf *msgbuf,
-			      struct replay_opts *opts)
-{
-	struct merge_options o;
-	struct tree *result, *next_tree, *base_tree, *head_tree;
-	int clean, index_fd;
-	const char **xopt;
-	static struct lock_file index_lock;
-
-	index_fd = hold_locked_index(&index_lock, 1);
-
-	read_cache();
-
-	init_merge_options(&o);
-	o.ancestor = base ? base_label : "(empty tree)";
-	o.branch1 = "HEAD";
-	o.branch2 = next ? next_label : "(empty tree)";
-
-	head_tree = parse_tree_indirect(head);
-	next_tree = next ? next->tree : empty_tree();
-	base_tree = base ? base->tree : empty_tree();
-
-	for (xopt = opts->xopts; xopt != opts->xopts + opts->xopts_nr; xopt++)
-		parse_merge_opt(&o, *xopt);
-
-	clean = merge_trees(&o,
-			    head_tree,
-			    next_tree, base_tree, &result);
-
-	if (active_cache_changed &&
-	    (write_cache(index_fd, active_cache, active_nr) ||
-	     commit_locked_index(&index_lock)))
-		/* TRANSLATORS: %s will be "revert" or "cherry-pick" */
-		die(_("%s: Unable to write new index file"), action_name(opts));
-	rollback_lock_file(&index_lock);
-
-	if (!clean) {
-		int i;
-		strbuf_addstr(msgbuf, "\nConflicts:\n\n");
-		for (i = 0; i < active_nr;) {
-			struct cache_entry *ce = active_cache[i++];
-			if (ce_stage(ce)) {
-				strbuf_addch(msgbuf, '\t');
-				strbuf_addstr(msgbuf, ce->name);
-				strbuf_addch(msgbuf, '\n');
-				while (i < active_nr && !strcmp(ce->name,
-						active_cache[i]->name))
-					i++;
-			}
-		}
-	}
-
-	return !clean;
-}
-
-/*
- * If we are cherry-pick, and if the merge did not result in
- * hand-editing, we will hit this commit and inherit the original
- * author date and name.
- * If we are revert, or if our cherry-pick results in a hand merge,
- * we had better say that the current user is responsible for that.
- */
-static int run_git_commit(const char *defmsg, struct replay_opts *opts)
-{
-	/* 6 is max possible length of our args array including NULL */
-	const char *args[6];
-	int i = 0;
-
-	args[i++] = "commit";
-	args[i++] = "-n";
-	if (opts->signoff)
-		args[i++] = "-s";
-	if (!opts->edit) {
-		args[i++] = "-F";
-		args[i++] = defmsg;
-	}
-	args[i] = NULL;
-
-	return run_command_v_opt(args, RUN_GIT_CMD);
-}
-
-static int do_pick_commit(struct commit *commit, struct replay_opts *opts)
-{
-	unsigned char head[20];
-	struct commit *base, *next, *parent;
-	const char *base_label, *next_label;
-	struct commit_message msg = { NULL, NULL, NULL, NULL, NULL };
-	char *defmsg = NULL;
-	struct strbuf msgbuf = STRBUF_INIT;
-	int res;
-
-	if (opts->no_commit) {
-		/*
-		 * We do not intend to commit immediately.  We just want to
-		 * merge the differences in, so let's compute the tree
-		 * that represents the "current" state for merge-recursive
-		 * to work on.
-		 */
-		if (write_cache_as_tree(head, 0, NULL))
-			die (_("Your index file is unmerged."));
-	} else {
-		if (get_sha1("HEAD", head))
-			return error(_("You do not have a valid HEAD"));
-		if (index_differs_from("HEAD", 0))
-			return error_dirty_index(opts);
-	}
-	discard_cache();
-
-	if (!commit->parents) {
-		parent = NULL;
-	}
-	else if (commit->parents->next) {
-		/* Reverting or cherry-picking a merge commit */
-		int cnt;
-		struct commit_list *p;
-
-		if (!opts->mainline)
-			return error(_("Commit %s is a merge but no -m option was given."),
-				sha1_to_hex(commit->object.sha1));
-
-		for (cnt = 1, p = commit->parents;
-		     cnt != opts->mainline && p;
-		     cnt++)
-			p = p->next;
-		if (cnt != opts->mainline || !p)
-			return error(_("Commit %s does not have parent %d"),
-				sha1_to_hex(commit->object.sha1), opts->mainline);
-		parent = p->item;
-	} else if (0 < opts->mainline)
-		return error(_("Mainline was specified but commit %s is not a merge."),
-			sha1_to_hex(commit->object.sha1));
-	else
-		parent = commit->parents->item;
-
-	if (opts->allow_ff && parent && !hashcmp(parent->object.sha1, head))
-		return fast_forward_to(commit->object.sha1, head);
-
-	if (parent && parse_commit(parent) < 0)
-		/* TRANSLATORS: The first %s will be "revert" or
-		   "cherry-pick", the second %s a SHA1 */
-		return error(_("%s: cannot parse parent commit %s"),
-			action_name(opts), sha1_to_hex(parent->object.sha1));
-
-	if (get_message(commit, &msg) != 0)
-		return error(_("Cannot get commit message for %s"),
-			sha1_to_hex(commit->object.sha1));
-
-	/*
-	 * "commit" is an existing commit.  We would want to apply
-	 * the difference it introduces since its first parent "prev"
-	 * on top of the current HEAD if we are cherry-pick.  Or the
-	 * reverse of it if we are revert.
-	 */
-
-	defmsg = git_pathdup("MERGE_MSG");
-
-	if (opts->action == REVERT) {
-		base = commit;
-		base_label = msg.label;
-		next = parent;
-		next_label = msg.parent_label;
-		strbuf_addstr(&msgbuf, "Revert \"");
-		strbuf_addstr(&msgbuf, msg.subject);
-		strbuf_addstr(&msgbuf, "\"\n\nThis reverts commit ");
-		strbuf_addstr(&msgbuf, sha1_to_hex(commit->object.sha1));
-
-		if (commit->parents && commit->parents->next) {
-			strbuf_addstr(&msgbuf, ", reversing\nchanges made to ");
-			strbuf_addstr(&msgbuf, sha1_to_hex(parent->object.sha1));
-		}
-		strbuf_addstr(&msgbuf, ".\n");
-	} else {
-		const char *p;
-
-		base = parent;
-		base_label = msg.parent_label;
-		next = commit;
-		next_label = msg.label;
-
-		/*
-		 * Append the commit log message to msgbuf; it starts
-		 * after the tree, parent, author, committer
-		 * information followed by "\n\n".
-		 */
-		p = strstr(msg.message, "\n\n");
-		if (p) {
-			p += 2;
-			strbuf_addstr(&msgbuf, p);
-		}
-
-		if (opts->record_origin) {
-			strbuf_addstr(&msgbuf, "(cherry picked from commit ");
-			strbuf_addstr(&msgbuf, sha1_to_hex(commit->object.sha1));
-			strbuf_addstr(&msgbuf, ")\n");
-		}
-	}
-
-	if (!opts->strategy || !strcmp(opts->strategy, "recursive") || opts->action == REVERT) {
-		res = do_recursive_merge(base, next, base_label, next_label,
-					 head, &msgbuf, opts);
-		write_message(&msgbuf, defmsg);
-	} else {
-		struct commit_list *common = NULL;
-		struct commit_list *remotes = NULL;
-
-		write_message(&msgbuf, defmsg);
-
-		commit_list_insert(base, &common);
-		commit_list_insert(next, &remotes);
-		res = try_merge_command(opts->strategy, opts->xopts_nr, opts->xopts,
-					common, sha1_to_hex(head), remotes);
-		free_commit_list(common);
-		free_commit_list(remotes);
-	}
-
-	/*
-	 * If the merge was clean or if it failed due to conflict, we write
-	 * CHERRY_PICK_HEAD for the subsequent invocation of commit to use.
-	 * However, if the merge did not even start, then we don't want to
-	 * write it at all.
-	 */
-	if (opts->action == CHERRY_PICK && !opts->no_commit && (res == 0 || res == 1))
-		write_cherry_pick_head(commit, "CHERRY_PICK_HEAD");
-	if (opts->action == REVERT && ((opts->no_commit && res == 0) || res == 1))
-		write_cherry_pick_head(commit, "REVERT_HEAD");
-
-	if (res) {
-		error(opts->action == REVERT
-		      ? _("could not revert %s... %s")
-		      : _("could not apply %s... %s"),
-		      find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV),
-		      msg.subject);
-		print_advice(res == 1);
-		rerere(opts->allow_rerere_auto);
-	} else {
-		if (!opts->no_commit)
-			res = run_git_commit(defmsg, opts);
-	}
-
-	free_message(&msg);
-	free(defmsg);
-
-	return res;
-}
-
-static void prepare_revs(struct replay_opts *opts)
-{
-	if (opts->action != REVERT)
-		opts->revs->reverse ^= 1;
-
-	if (prepare_revision_walk(opts->revs))
-		die(_("revision walk setup failed"));
-
-	if (!opts->revs->commits)
-		die(_("empty commit set passed"));
-}
-
-static void read_and_refresh_cache(struct replay_opts *opts)
-{
-	static struct lock_file index_lock;
-	int index_fd = hold_locked_index(&index_lock, 0);
-	if (read_index_preload(&the_index, NULL) < 0)
-		die(_("git %s: failed to read the index"), action_name(opts));
-	refresh_index(&the_index, REFRESH_QUIET|REFRESH_UNMERGED, NULL, NULL, NULL);
-	if (the_index.cache_changed) {
-		if (write_index(&the_index, index_fd) ||
-		    commit_locked_index(&index_lock))
-			die(_("git %s: failed to refresh the index"), action_name(opts));
-	}
-	rollback_lock_file(&index_lock);
-}
-
-/*
- * Append a commit to the end of the commit_list.
- *
- * next starts by pointing to the variable that holds the head of an
- * empty commit_list, and is updated to point to the "next" field of
- * the last item on the list as new commits are appended.
- *
- * Usage example:
- *
- *     struct commit_list *list;
- *     struct commit_list **next = &list;
- *
- *     next = commit_list_append(c1, next);
- *     next = commit_list_append(c2, next);
- *     assert(commit_list_count(list) == 2);
- *     return list;
- */
-static struct commit_list **commit_list_append(struct commit *commit,
-					       struct commit_list **next)
-{
-	struct commit_list *new = xmalloc(sizeof(struct commit_list));
-	new->item = commit;
-	*next = new;
-	new->next = NULL;
-	return &new->next;
-}
-
-static int format_todo(struct strbuf *buf, struct commit_list *todo_list,
-		struct replay_opts *opts)
-{
-	struct commit_list *cur = NULL;
-	const char *sha1_abbrev = NULL;
-	const char *action_str = opts->action == REVERT ? "revert" : "pick";
-	const char *subject;
-	int subject_len;
-
-	for (cur = todo_list; cur; cur = cur->next) {
-		sha1_abbrev = find_unique_abbrev(cur->item->object.sha1, DEFAULT_ABBREV);
-		subject_len = find_commit_subject(cur->item->buffer, &subject);
-		strbuf_addf(buf, "%s %s %.*s\n", action_str, sha1_abbrev,
-			subject_len, subject);
-	}
-	return 0;
-}
-
-static struct commit *parse_insn_line(char *bol, char *eol, struct replay_opts *opts)
-{
-	unsigned char commit_sha1[20];
-	enum replay_action action;
-	char *end_of_object_name;
-	int saved, status, padding;
-
-	if (!prefixcmp(bol, "pick")) {
-		action = CHERRY_PICK;
-		bol += strlen("pick");
-	} else if (!prefixcmp(bol, "revert")) {
-		action = REVERT;
-		bol += strlen("revert");
-	} else
-		return NULL;
-
-	/* Eat up extra spaces/ tabs before object name */
-	padding = strspn(bol, " \t");
-	if (!padding)
-		return NULL;
-	bol += padding;
-
-	end_of_object_name = bol + strcspn(bol, " \t\n");
-	saved = *end_of_object_name;
-	*end_of_object_name = '\0';
-	status = get_sha1(bol, commit_sha1);
-	*end_of_object_name = saved;
-
-	/*
-	 * Verify that the action matches up with the one in
-	 * opts; we don't support arbitrary instructions
-	 */
-	if (action != opts->action) {
-		const char *action_str;
-		action_str = action == REVERT ? "revert" : "cherry-pick";
-		error(_("Cannot %s during a %s"), action_str, action_name(opts));
-		return NULL;
-	}
-
-	if (status < 0)
-		return NULL;
-
-	return lookup_commit_reference(commit_sha1);
-}
-
-static int parse_insn_buffer(char *buf, struct commit_list **todo_list,
-			struct replay_opts *opts)
-{
-	struct commit_list **next = todo_list;
-	struct commit *commit;
-	char *p = buf;
-	int i;
-
-	for (i = 1; *p; i++) {
-		char *eol = strchrnul(p, '\n');
-		commit = parse_insn_line(p, eol, opts);
-		if (!commit)
-			return error(_("Could not parse line %d."), i);
-		next = commit_list_append(commit, next);
-		p = *eol ? eol + 1 : eol;
-	}
-	if (!*todo_list)
-		return error(_("No commits parsed."));
-	return 0;
-}
-
-static void read_populate_todo(struct commit_list **todo_list,
-			struct replay_opts *opts)
-{
-	const char *todo_file = git_path(SEQ_TODO_FILE);
-	struct strbuf buf = STRBUF_INIT;
-	int fd, res;
-
-	fd = open(todo_file, O_RDONLY);
-	if (fd < 0)
-		die_errno(_("Could not open %s"), todo_file);
-	if (strbuf_read(&buf, fd, 0) < 0) {
-		close(fd);
-		strbuf_release(&buf);
-		die(_("Could not read %s."), todo_file);
-	}
-	close(fd);
-
-	res = parse_insn_buffer(buf.buf, todo_list, opts);
-	strbuf_release(&buf);
-	if (res)
-		die(_("Unusable instruction sheet: %s"), todo_file);
-}
-
-static int populate_opts_cb(const char *key, const char *value, void *data)
-{
-	struct replay_opts *opts = data;
-	int error_flag = 1;
-
-	if (!value)
-		error_flag = 0;
-	else if (!strcmp(key, "options.no-commit"))
-		opts->no_commit = git_config_bool_or_int(key, value, &error_flag);
-	else if (!strcmp(key, "options.edit"))
-		opts->edit = git_config_bool_or_int(key, value, &error_flag);
-	else if (!strcmp(key, "options.signoff"))
-		opts->signoff = git_config_bool_or_int(key, value, &error_flag);
-	else if (!strcmp(key, "options.record-origin"))
-		opts->record_origin = git_config_bool_or_int(key, value, &error_flag);
-	else if (!strcmp(key, "options.allow-ff"))
-		opts->allow_ff = git_config_bool_or_int(key, value, &error_flag);
-	else if (!strcmp(key, "options.mainline"))
-		opts->mainline = git_config_int(key, value);
-	else if (!strcmp(key, "options.strategy"))
-		git_config_string(&opts->strategy, key, value);
-	else if (!strcmp(key, "options.strategy-option")) {
-		ALLOC_GROW(opts->xopts, opts->xopts_nr + 1, opts->xopts_alloc);
-		opts->xopts[opts->xopts_nr++] = xstrdup(value);
-	} else
-		return error(_("Invalid key: %s"), key);
-
-	if (!error_flag)
-		return error(_("Invalid value for %s: %s"), key, value);
-
-	return 0;
-}
-
-static void read_populate_opts(struct replay_opts **opts_ptr)
-{
-	const char *opts_file = git_path(SEQ_OPTS_FILE);
-
-	if (!file_exists(opts_file))
-		return;
-	if (git_config_from_file(populate_opts_cb, opts_file, *opts_ptr) < 0)
-		die(_("Malformed options sheet: %s"), opts_file);
-}
-
-static void walk_revs_populate_todo(struct commit_list **todo_list,
-				struct replay_opts *opts)
-{
-	struct commit *commit;
-	struct commit_list **next;
-
-	prepare_revs(opts);
-
-	next = todo_list;
-	while ((commit = get_revision(opts->revs)))
-		next = commit_list_append(commit, next);
-}
-
-static int create_seq_dir(void)
-{
-	const char *seq_dir = git_path(SEQ_DIR);
-
-	if (file_exists(seq_dir)) {
-		error(_("a cherry-pick or revert is already in progress"));
-		advise(_("try \"git cherry-pick (--continue | --quit | --abort)\""));
-		return -1;
-	}
-	else if (mkdir(seq_dir, 0777) < 0)
-		die_errno(_("Could not create sequencer directory %s"), seq_dir);
-	return 0;
-}
-
-static void save_head(const char *head)
-{
-	const char *head_file = git_path(SEQ_HEAD_FILE);
-	static struct lock_file head_lock;
-	struct strbuf buf = STRBUF_INIT;
-	int fd;
-
-	fd = hold_lock_file_for_update(&head_lock, head_file, LOCK_DIE_ON_ERROR);
-	strbuf_addf(&buf, "%s\n", head);
-	if (write_in_full(fd, buf.buf, buf.len) < 0)
-		die_errno(_("Could not write to %s"), head_file);
-	if (commit_lock_file(&head_lock) < 0)
-		die(_("Error wrapping up %s."), head_file);
-}
-
-static int reset_for_rollback(const unsigned char *sha1)
-{
-	const char *argv[4];	/* reset --merge <arg> + NULL */
-	argv[0] = "reset";
-	argv[1] = "--merge";
-	argv[2] = sha1_to_hex(sha1);
-	argv[3] = NULL;
-	return run_command_v_opt(argv, RUN_GIT_CMD);
-}
-
-static int rollback_single_pick(void)
-{
-	unsigned char head_sha1[20];
-
-	if (!file_exists(git_path("CHERRY_PICK_HEAD")) &&
-	    !file_exists(git_path("REVERT_HEAD")))
-		return error(_("no cherry-pick or revert in progress"));
-	if (read_ref_full("HEAD", head_sha1, 0, NULL))
-		return error(_("cannot resolve HEAD"));
-	if (is_null_sha1(head_sha1))
-		return error(_("cannot abort from a branch yet to be born"));
-	return reset_for_rollback(head_sha1);
-}
-
-static int sequencer_rollback(struct replay_opts *opts)
-{
-	const char *filename;
-	FILE *f;
-	unsigned char sha1[20];
-	struct strbuf buf = STRBUF_INIT;
-
-	filename = git_path(SEQ_HEAD_FILE);
-	f = fopen(filename, "r");
-	if (!f && errno == ENOENT) {
-		/*
-		 * There is no multiple-cherry-pick in progress.
-		 * If CHERRY_PICK_HEAD or REVERT_HEAD indicates
-		 * a single-cherry-pick in progress, abort that.
-		 */
-		return rollback_single_pick();
-	}
-	if (!f)
-		return error(_("cannot open %s: %s"), filename,
-						strerror(errno));
-	if (strbuf_getline(&buf, f, '\n')) {
-		error(_("cannot read %s: %s"), filename, ferror(f) ?
-			strerror(errno) : _("unexpected end of file"));
-		fclose(f);
-		goto fail;
-	}
-	fclose(f);
-	if (get_sha1_hex(buf.buf, sha1) || buf.buf[40] != '\0') {
-		error(_("stored pre-cherry-pick HEAD file '%s' is corrupt"),
-			filename);
-		goto fail;
-	}
-	if (reset_for_rollback(sha1))
-		goto fail;
-	remove_sequencer_state();
-	strbuf_release(&buf);
-	return 0;
-fail:
-	strbuf_release(&buf);
-	return -1;
-}
-
-static void save_todo(struct commit_list *todo_list, struct replay_opts *opts)
-{
-	const char *todo_file = git_path(SEQ_TODO_FILE);
-	static struct lock_file todo_lock;
-	struct strbuf buf = STRBUF_INIT;
-	int fd;
-
-	fd = hold_lock_file_for_update(&todo_lock, todo_file, LOCK_DIE_ON_ERROR);
-	if (format_todo(&buf, todo_list, opts) < 0)
-		die(_("Could not format %s."), todo_file);
-	if (write_in_full(fd, buf.buf, buf.len) < 0) {
-		strbuf_release(&buf);
-		die_errno(_("Could not write to %s"), todo_file);
-	}
-	if (commit_lock_file(&todo_lock) < 0) {
-		strbuf_release(&buf);
-		die(_("Error wrapping up %s."), todo_file);
-	}
-	strbuf_release(&buf);
-}
-
-static void save_opts(struct replay_opts *opts)
-{
-	const char *opts_file = git_path(SEQ_OPTS_FILE);
-
-	if (opts->no_commit)
-		git_config_set_in_file(opts_file, "options.no-commit", "true");
-	if (opts->edit)
-		git_config_set_in_file(opts_file, "options.edit", "true");
-	if (opts->signoff)
-		git_config_set_in_file(opts_file, "options.signoff", "true");
-	if (opts->record_origin)
-		git_config_set_in_file(opts_file, "options.record-origin", "true");
-	if (opts->allow_ff)
-		git_config_set_in_file(opts_file, "options.allow-ff", "true");
-	if (opts->mainline) {
-		struct strbuf buf = STRBUF_INIT;
-		strbuf_addf(&buf, "%d", opts->mainline);
-		git_config_set_in_file(opts_file, "options.mainline", buf.buf);
-		strbuf_release(&buf);
-	}
-	if (opts->strategy)
-		git_config_set_in_file(opts_file, "options.strategy", opts->strategy);
-	if (opts->xopts) {
-		int i;
-		for (i = 0; i < opts->xopts_nr; i++)
-			git_config_set_multivar_in_file(opts_file,
-							"options.strategy-option",
-							opts->xopts[i], "^$", 0);
-	}
-}
-
-static int pick_commits(struct commit_list *todo_list, struct replay_opts *opts)
-{
-	struct commit_list *cur;
-	int res;
-
-	setenv(GIT_REFLOG_ACTION, action_name(opts), 0);
-	if (opts->allow_ff)
-		assert(!(opts->signoff || opts->no_commit ||
-				opts->record_origin || opts->edit));
-	read_and_refresh_cache(opts);
-
-	for (cur = todo_list; cur; cur = cur->next) {
-		save_todo(cur, opts);
-		res = do_pick_commit(cur->item, opts);
-		if (res)
-			return res;
-	}
-
-	/*
-	 * Sequence of picks finished successfully; cleanup by
-	 * removing the .git/sequencer directory
-	 */
-	remove_sequencer_state();
-	return 0;
-}
-
-static int continue_single_pick(void)
-{
-	const char *argv[] = { "commit", NULL };
-
-	if (!file_exists(git_path("CHERRY_PICK_HEAD")) &&
-	    !file_exists(git_path("REVERT_HEAD")))
-		return error(_("no cherry-pick or revert in progress"));
-	return run_command_v_opt(argv, RUN_GIT_CMD);
-}
-
-static int sequencer_continue(struct replay_opts *opts)
-{
-	struct commit_list *todo_list = NULL;
-
-	if (!file_exists(git_path(SEQ_TODO_FILE)))
-		return continue_single_pick();
-	read_populate_opts(&opts);
-	read_populate_todo(&todo_list, opts);
-
-	/* Verify that the conflict has been resolved */
-	if (file_exists(git_path("CHERRY_PICK_HEAD")) ||
-	    file_exists(git_path("REVERT_HEAD"))) {
-		int ret = continue_single_pick();
-		if (ret)
-			return ret;
-	}
-	if (index_differs_from("HEAD", 0))
-		return error_dirty_index(opts);
-	todo_list = todo_list->next;
-	return pick_commits(todo_list, opts);
-}
-
-static int single_pick(struct commit *cmit, struct replay_opts *opts)
-{
-	setenv(GIT_REFLOG_ACTION, action_name(opts), 0);
-	return do_pick_commit(cmit, opts);
-}
-
-static int pick_revisions(struct replay_opts *opts)
-{
-	struct commit_list *todo_list = NULL;
-	unsigned char sha1[20];
-
-	if (opts->subcommand == REPLAY_NONE)
-		assert(opts->revs);
-
-	read_and_refresh_cache(opts);
-
-	/*
-	 * Decide what to do depending on the arguments; a fresh
-	 * cherry-pick should be handled differently from an existing
-	 * one that is being continued
-	 */
-	if (opts->subcommand == REPLAY_REMOVE_STATE) {
-		remove_sequencer_state();
-		return 0;
-	}
-	if (opts->subcommand == REPLAY_ROLLBACK)
-		return sequencer_rollback(opts);
-	if (opts->subcommand == REPLAY_CONTINUE)
-		return sequencer_continue(opts);
-
-	/*
-	 * If we were called as "git cherry-pick <commit>", just
-	 * cherry-pick/revert it, set CHERRY_PICK_HEAD /
-	 * REVERT_HEAD, and don't touch the sequencer state.
-	 * This means it is possible to cherry-pick in the middle
-	 * of a cherry-pick sequence.
-	 */
-	if (opts->revs->cmdline.nr == 1 &&
-	    opts->revs->cmdline.rev->whence == REV_CMD_REV &&
-	    opts->revs->no_walk &&
-	    !opts->revs->cmdline.rev->flags) {
-		struct commit *cmit;
-		if (prepare_revision_walk(opts->revs))
-			die(_("revision walk setup failed"));
-		cmit = get_revision(opts->revs);
-		if (!cmit || get_revision(opts->revs))
-			die("BUG: expected exactly one commit from walk");
-		return single_pick(cmit, opts);
-	}
-
-	/*
-	 * Start a new cherry-pick/ revert sequence; but
-	 * first, make sure that an existing one isn't in
-	 * progress
-	 */
-
-	walk_revs_populate_todo(&todo_list, opts);
-	if (create_seq_dir() < 0)
-		return -1;
-	if (get_sha1("HEAD", sha1)) {
-		if (opts->action == REVERT)
-			return error(_("Can't revert as initial commit"));
-		return error(_("Can't cherry-pick into empty head"));
-	}
-	save_head(sha1_to_hex(sha1));
-	save_opts(opts);
-	return pick_commits(todo_list, opts);
-}
-
 int cmd_revert(int argc, const char **argv, const char *prefix)
 {
 	struct replay_opts opts;
@@ -1141,10 +201,10 @@ int cmd_revert(int argc, const char **argv, const char *prefix)
 	memset(&opts, 0, sizeof(opts));
 	if (isatty(0))
 		opts.edit = 1;
-	opts.action = REVERT;
+	opts.action = REPLAY_REVERT;
 	git_config(git_default_config, NULL);
 	parse_args(argc, argv, &opts);
-	res = pick_revisions(&opts);
+	res = sequencer_pick_revisions(&opts);
 	if (res < 0)
 		die(_("revert failed"));
 	return res;
@@ -1156,10 +216,10 @@ int cmd_cherry_pick(int argc, const char **argv, const char *prefix)
 	int res;
 
 	memset(&opts, 0, sizeof(opts));
-	opts.action = CHERRY_PICK;
+	opts.action = REPLAY_PICK;
 	git_config(git_default_config, NULL);
 	parse_args(argc, argv, &opts);
-	res = pick_revisions(&opts);
+	res = sequencer_pick_revisions(&opts);
 	if (res < 0)
 		die(_("cherry-pick failed"));
 	return res;