1 files changed, 52 insertions, 1 deletions

diff --git a/builtin/branch.c b/builtin/branch.c
index 6371bf96c4..e09ce51c2e 100644
--- a/builtin/branch.c
+++ b/builtin/branch.c
@@ -18,6 +18,7 @@
 #include "string-list.h"
 #include "column.h"
 #include "utf8.h"
+#include "wt-status.h"
 
 static const char * const builtin_branch_usage[] = {
 	N_("git branch [options] [-r | -a] [--merged | --no-merged]"),
@@ -550,6 +551,29 @@ static int calc_maxwidth(struct ref_list *refs)
 	return w;
 }
 
+static char *get_head_description(void)
+{
+	struct strbuf desc = STRBUF_INIT;
+	struct wt_status_state state;
+	memset(&state, 0, sizeof(state));
+	wt_status_get_state(&state, 1);
+	if (state.rebase_in_progress ||
+	    state.rebase_interactive_in_progress)
+		strbuf_addf(&desc, _("(no branch, rebasing %s)"),
+			    state.branch);
+	else if (state.bisect_in_progress)
+		strbuf_addf(&desc, _("(no branch, bisect started on %s)"),
+			    state.branch);
+	else if (state.detached_from)
+		strbuf_addf(&desc, _("(detached from %s)"),
+			    state.detached_from);
+	else
+		strbuf_addstr(&desc, _("(no branch)"));
+	free(state.branch);
+	free(state.onto);
+	free(state.detached_from);
+	return strbuf_detach(&desc, NULL);
+}
 
 static void show_detached(struct ref_list *ref_list)
 {
@@ -557,7 +581,7 @@ static void show_detached(struct ref_list *ref_list)
 
 	if (head_commit && is_descendant_of(head_commit, ref_list->with_commit)) {
 		struct ref_item item;
-		item.name = xstrdup(_("(no branch)"));
+		item.name = get_head_description();
 		item.width = utf8_strwidth(item.name);
 		item.kind = REF_LOCAL_BRANCH;
 		item.dest = NULL;
@@ -889,6 +913,17 @@ int cmd_branch(int argc, const char **argv, const char *prefix)
 	} else if (new_upstream) {
 		struct branch *branch = branch_get(argv[0]);
 
+		if (argc > 1)
+			die(_("too many branches to set new upstream"));
+
+		if (!branch) {
+			if (!argc || !strcmp(argv[0], "HEAD"))
+				die(_("could not set upstream of HEAD to %s when "
+				      "it does not point to any branch."),
+				    new_upstream);
+			die(_("no such branch '%s'"), argv[0]);
+		}
+
 		if (!ref_exists(branch->refname))
 			die(_("branch '%s' does not exist"), branch->name);
 
@@ -901,6 +936,16 @@ int cmd_branch(int argc, const char **argv, const char *prefix)
 		struct branch *branch = branch_get(argv[0]);
 		struct strbuf buf = STRBUF_INIT;
 
+		if (argc > 1)
+			die(_("too many branches to unset upstream"));
+
+		if (!branch) {
+			if (!argc || !strcmp(argv[0], "HEAD"))
+				die(_("could not unset upstream of HEAD when "
+				      "it does not point to any branch."));
+			die(_("no such branch '%s'"), argv[0]);
+		}
+
 		if (!branch_has_merge_config(branch)) {
 			die(_("Branch '%s' has no upstream information"), branch->name);
 		}
@@ -916,6 +961,12 @@ int cmd_branch(int argc, const char **argv, const char *prefix)
 		int branch_existed = 0, remote_tracking = 0;
 		struct strbuf buf = STRBUF_INIT;
 
+		if (!strcmp(argv[0], "HEAD"))
+			die(_("it does not make sense to create 'HEAD' manually"));
+
+		if (!branch)
+			die(_("no such branch '%s'"), argv[0]);
+
 		if (kinds != REF_LOCAL_BRANCH)
 			die(_("-a and -r options to 'git branch' do not make sense with a branch name"));