1 files changed, 371 insertions, 279 deletions

diff --git a/git-rebase.sh b/git-rebase.sh
index dd7dfe123c..03f73da887 100755
--- a/git-rebase.sh
+++ b/git-rebase.sh
@@ -3,7 +3,7 @@
 # Copyright (c) 2005 Junio C Hamano.
 #
 
-USAGE='[--interactive | -i] [-v] [--onto <newbase>] <upstream> [<branch>]'
+USAGE='[--interactive | -i] [-v] [--force-rebase | -f] [--no-ff] [--onto <newbase>] [<upstream>|--root] [<branch>] [--quiet | -q]'
 LONG_USAGE='git-rebase replaces <branch> with a new branch of the
 same name.  When the --onto option is provided the new branch starts
 out with a HEAD equal to <newbase>, otherwise it is equal to <upstream>
@@ -13,322 +13,435 @@ It then attempts to create a new commit for each commit from the original
 It is possible that a merge failure will prevent this process from being
 completely automatic.  You will have to resolve any such merge failure
 and run git rebase --continue.  Another option is to bypass the commit
-that caused the merge failure with git rebase --skip.  To restore the
-original <branch> and remove the .dotest working files, use the command
-git rebase --abort instead.
+that caused the merge failure with git rebase --skip.  To check out the
+original <branch> and remove the .git/rebase-apply working files, use the
+command git rebase --abort instead.
 
 Note that if <branch> is not specified on the command line, the
 currently checked out branch is used.
 
 Example:       git-rebase master~1 topic
 
-        A---B---C topic                   A'\''--B'\''--C'\'' topic
+	A---B---C topic                   A'\''--B'\''--C'\'' topic
        /                   -->           /
   D---E---F---G master          D---E---F---G master
 '
 
 SUBDIRECTORY_OK=Yes
-OPTIONS_SPEC=
+OPTIONS_KEEPDASHDASH=
+OPTIONS_SPEC="\
+git rebase [-i] [options] [--onto <newbase>] [<upstream>] [<branch>]
+git rebase [-i] [options] --onto <newbase> --root [<branch>]
+git-rebase [-i] --continue | --abort | --skip
+--
+ Available options are
+v,verbose!         display a diffstat of what changed upstream
+q,quiet!           be quiet. implies --no-stat
+onto=!             rebase onto given branch instead of upstream
+p,preserve-merges! try to recreate merges instead of ignoring them
+s,strategy=!       use the given merge strategy
+no-ff!             cherry-pick all commits, even if unchanged
+m,merge!           use merging strategies to rebase
+i,interactive!     let the user edit the list of commits to rebase
+f,force-rebase!    force rebase even if branch is up to date
+X,strategy-option=! pass the argument through to the merge strategy
+stat!              display a diffstat of what changed upstream
+n,no-stat!         do not show diffstat of what changed upstream
+verify             allow pre-rebase hook to run
+rerere-autoupdate  allow rerere to update index with resolved conflicts
+root!              rebase all reachable commits up to the root(s)
+autosquash         move commits that begin with squash!/fixup! under -i
+committer-date-is-author-date! passed to 'git am'
+ignore-date!       passed to 'git am'
+whitespace=!       passed to 'git apply'
+ignore-whitespace! passed to 'git apply'
+C=!                passed to 'git apply'
+ Actions:
+continue!          continue
+abort!             abort and check out the original branch
+skip!              skip current patch and continue
+"
 . git-sh-setup
 set_reflog_action rebase
-require_work_tree
+require_work_tree_exists
 cd_to_toplevel
 
-RESOLVEMSG="
+LF='
+'
+ok_to_skip_pre_rebase=
+resolvemsg="
 When you have resolved this problem run \"git rebase --continue\".
 If you would prefer to skip this patch, instead run \"git rebase --skip\".
-To restore the original branch and stop rebasing run \"git rebase --abort\".
+To check out the original branch and stop rebasing run \"git rebase --abort\".
 "
-unset newbase
-strategy=recursive
+unset onto
+strategy=
+strategy_opts=
 do_merge=
-dotest=$GIT_DIR/.dotest-merge
-prec=4
+merge_dir="$GIT_DIR"/rebase-merge
+apply_dir="$GIT_DIR"/rebase-apply
 verbose=
+diffstat=
+test "$(git config --bool rebase.stat)" = true && diffstat=t
 git_am_opt=
-
-continue_merge () {
-	test -n "$prev_head" || die "prev_head must be defined"
-	test -d "$dotest" || die "$dotest directory does not exist"
-
-	unmerged=$(git ls-files -u)
-	if test -n "$unmerged"
+rebase_root=
+force_rebase=
+allow_rerere_autoupdate=
+# Non-empty if a rebase was in progress when 'git rebase' was invoked
+in_progress=
+# One of {am, merge, interactive}
+type=
+# One of {"$GIT_DIR"/rebase-apply, "$GIT_DIR"/rebase-merge}
+state_dir=
+# One of {'', continue, skip, abort}, as parsed from command line
+action=
+preserve_merges=
+autosquash=
+test "$(git config --bool rebase.autosquash)" = "true" && autosquash=t
+
+read_basic_state () {
+	head_name=$(cat "$state_dir"/head-name) &&
+	onto=$(cat "$state_dir"/onto) &&
+	# We always write to orig-head, but interactive rebase used to write to
+	# head. Fall back to reading from head to cover for the case that the
+	# user upgraded git with an ongoing interactive rebase.
+	if test -f "$state_dir"/orig-head
 	then
-		echo "You still have unmerged paths in your index"
-		echo "did you forget to use git add?"
-		die "$RESOLVEMSG"
-	fi
-
-	cmt=`cat "$dotest/current"`
-	if ! git diff-index --quiet --ignore-submodules HEAD --
-	then
-		if ! git commit --no-verify -C "$cmt"
-		then
-			echo "Commit failed, please do not call \"git commit\""
-			echo "directly, but instead do one of the following: "
-			die "$RESOLVEMSG"
-		fi
-		printf "Committed: %0${prec}d " $msgnum
+		orig_head=$(cat "$state_dir"/orig-head)
 	else
-		printf "Already applied: %0${prec}d " $msgnum
-	fi
-	git rev-list --pretty=oneline -1 "$cmt" | sed -e 's/^[^ ]* //'
-
-	prev_head=`git rev-parse HEAD^0`
-	# save the resulting commit so we can read-tree on it later
-	echo "$prev_head" > "$dotest/prev_head"
+		orig_head=$(cat "$state_dir"/head)
+	fi &&
+	GIT_QUIET=$(cat "$state_dir"/quiet) &&
+	test -f "$state_dir"/verbose && verbose=t
+	test -f "$state_dir"/strategy && strategy="$(cat "$state_dir"/strategy)"
+	test -f "$state_dir"/strategy_opts &&
+		strategy_opts="$(cat "$state_dir"/strategy_opts)"
+	test -f "$state_dir"/allow_rerere_autoupdate &&
+		allow_rerere_autoupdate="$(cat "$state_dir"/allow_rerere_autoupdate)"
+}
 
-	# onto the next patch:
-	msgnum=$(($msgnum + 1))
-	echo "$msgnum" >"$dotest/msgnum"
+write_basic_state () {
+	echo "$head_name" > "$state_dir"/head-name &&
+	echo "$onto" > "$state_dir"/onto &&
+	echo "$orig_head" > "$state_dir"/orig-head &&
+	echo "$GIT_QUIET" > "$state_dir"/quiet &&
+	test t = "$verbose" && : > "$state_dir"/verbose
+	test -n "$strategy" && echo "$strategy" > "$state_dir"/strategy
+	test -n "$strategy_opts" && echo "$strategy_opts" > \
+		"$state_dir"/strategy_opts
+	test -n "$allow_rerere_autoupdate" && echo "$allow_rerere_autoupdate" > \
+		"$state_dir"/allow_rerere_autoupdate
 }
 
-call_merge () {
-	cmt="$(cat "$dotest/cmt.$1")"
-	echo "$cmt" > "$dotest/current"
-	hd=$(git rev-parse --verify HEAD)
-	cmt_name=$(git symbolic-ref HEAD 2> /dev/null || echo HEAD)
-	msgnum=$(cat "$dotest/msgnum")
-	end=$(cat "$dotest/end")
-	eval GITHEAD_$cmt='"${cmt_name##refs/heads/}~$(($end - $msgnum))"'
-	eval GITHEAD_$hd='$(cat "$dotest/onto_name")'
-	export GITHEAD_$cmt GITHEAD_$hd
-	git-merge-$strategy "$cmt^" -- "$hd" "$cmt"
-	rv=$?
-	case "$rv" in
-	0)
-		unset GITHEAD_$cmt GITHEAD_$hd
-		return
-		;;
-	1)
-		git rerere
-		die "$RESOLVEMSG"
-		;;
-	2)
-		echo "Strategy: $rv $strategy failed, try another" 1>&2
-		die "$RESOLVEMSG"
+output () {
+	case "$verbose" in
+	'')
+		output=$("$@" 2>&1 )
+		status=$?
+		test $status != 0 && printf "%s\n" "$output"
+		return $status
 		;;
 	*)
-		die "Unknown exit code ($rv) from command:" \
-			"git-merge-$strategy $cmt^ -- HEAD $cmt"
+		"$@"
 		;;
 	esac
 }
 
 move_to_original_branch () {
-	test -z "$head_name" &&
-		head_name="$(cat "$dotest"/head-name)" &&
-		onto="$(cat "$dotest"/onto)" &&
-		orig_head="$(cat "$dotest"/orig-head)"
 	case "$head_name" in
 	refs/*)
 		message="rebase finished: $head_name onto $onto"
 		git update-ref -m "$message" \
 			$head_name $(git rev-parse HEAD) $orig_head &&
-		git symbolic-ref HEAD $head_name ||
+		git symbolic-ref \
+			-m "rebase finished: returning to $head_name" \
+			HEAD $head_name ||
 		die "Could not move back to $head_name"
 		;;
 	esac
 }
 
-finish_rb_merge () {
-	move_to_original_branch
-	rm -r "$dotest"
-	echo "All done."
+run_specific_rebase () {
+	if [ "$interactive_rebase" = implied ]; then
+		GIT_EDITOR=:
+		export GIT_EDITOR
+	fi
+	. git-rebase--$type
 }
 
-is_interactive () {
-	test -f "$dotest"/interactive ||
-	while :; do case $#,"$1" in 0,|*,-i|*,--interactive) break ;; esac
-		shift
-	done && test -n "$1"
+run_pre_rebase_hook () {
+	if test -z "$ok_to_skip_pre_rebase" &&
+	   test -x "$GIT_DIR/hooks/pre-rebase"
+	then
+		"$GIT_DIR/hooks/pre-rebase" ${1+"$@"} ||
+		die "The pre-rebase hook refused to rebase."
+	fi
 }
 
-is_interactive "$@" && exec git-rebase--interactive "$@"
+test -f "$apply_dir"/applying &&
+	die 'It looks like git-am is in progress. Cannot rebase.'
 
+if test -d "$apply_dir"
+then
+	type=am
+	state_dir="$apply_dir"
+elif test -d "$merge_dir"
+then
+	if test -f "$merge_dir"/interactive
+	then
+		type=interactive
+		interactive_rebase=explicit
+	else
+		type=merge
+	fi
+	state_dir="$merge_dir"
+fi
+test -n "$type" && in_progress=t
+
+total_argc=$#
 while test $# != 0
 do
 	case "$1" in
-	--continue)
-		git diff-files --quiet --ignore-submodules || {
-			echo "You must edit all merge conflicts and then"
-			echo "mark them as resolved using git add"
-			exit 1
-		}
-		if test -d "$dotest"
-		then
-			prev_head=$(cat "$dotest/prev_head")
-			end=$(cat "$dotest/end")
-			msgnum=$(cat "$dotest/msgnum")
-			onto=$(cat "$dotest/onto")
-			continue_merge
-			while test "$msgnum" -le "$end"
-			do
-				call_merge "$msgnum"
-				continue_merge
-			done
-			finish_rb_merge
-			exit
-		fi
-		head_name=$(cat .dotest/head-name) &&
-		onto=$(cat .dotest/onto) &&
-		orig_head=$(cat .dotest/orig-head) &&
-		git am --resolved --3way --resolvemsg="$RESOLVEMSG" &&
-		move_to_original_branch
-		exit
+	--no-verify)
+		ok_to_skip_pre_rebase=yes
 		;;
-	--skip)
-		git reset --hard HEAD || exit $?
-		if test -d "$dotest"
-		then
-			git rerere clear
-			prev_head=$(cat "$dotest/prev_head")
-			end=$(cat "$dotest/end")
-			msgnum=$(cat "$dotest/msgnum")
-			msgnum=$(($msgnum + 1))
-			onto=$(cat "$dotest/onto")
-			while test "$msgnum" -le "$end"
-			do
-				call_merge "$msgnum"
-				continue_merge
-			done
-			finish_rb_merge
-			exit
-		fi
-		head_name=$(cat .dotest/head-name) &&
-		onto=$(cat .dotest/onto) &&
-		orig_head=$(cat .dotest/orig-head) &&
-		git am -3 --skip --resolvemsg="$RESOLVEMSG" &&
-		move_to_original_branch
-		exit
+	--verify)
+		ok_to_skip_pre_rebase=
 		;;
-	--abort)
-		git rerere clear
-		if test -d "$dotest"
-		then
-			move_to_original_branch
-		elif test -d .dotest
-		then
-			dotest=.dotest
-			move_to_original_branch
-		else
-			die "No rebase in progress?"
-		fi
-		git reset --hard $(cat "$dotest/orig-head")
-		rm -r "$dotest"
-		exit
+	--continue|--skip|--abort)
+		test $total_argc -eq 2 || usage
+		action=${1##--}
 		;;
 	--onto)
 		test 2 -le "$#" || usage
-		newbase="$2"
+		onto="$2"
 		shift
 		;;
-	-M|-m|--m|--me|--mer|--merg|--merge)
+	-i)
+		interactive_rebase=explicit
+		;;
+	-p)
+		preserve_merges=t
+		test -z "$interactive_rebase" && interactive_rebase=implied
+		;;
+	--autosquash)
+		autosquash=t
+		;;
+	--no-autosquash)
+		autosquash=
+		;;
+	-M|-m)
 		do_merge=t
 		;;
-	-s=*|--s=*|--st=*|--str=*|--stra=*|--strat=*|--strate=*|\
-		--strateg=*|--strategy=*|\
-	-s|--s|--st|--str|--stra|--strat|--strate|--strateg|--strategy)
-		case "$#,$1" in
-		*,*=*)
-			strategy=`expr "z$1" : 'z-[^=]*=\(.*\)'` ;;
-		1,*)
-			usage ;;
-		*)
-			strategy="$2"
-			shift ;;
-		esac
+	-X)
+		shift
+		strategy_opts="$strategy_opts $(git rev-parse --sq-quote "--$1")"
 		do_merge=t
+		test -z "$strategy" && strategy=recursive
+		;;
+	-s)
+		shift
+		strategy="$1"
+		do_merge=t
+		;;
+	-n)
+		diffstat=
+		;;
+	--stat)
+		diffstat=t
 		;;
-	-v|--verbose)
+	-v)
 		verbose=t
+		diffstat=t
+		GIT_QUIET=
 		;;
-	--whitespace=*)
+	-q)
+		GIT_QUIET=t
+		git_am_opt="$git_am_opt -q"
+		verbose=
+		diffstat=
+		;;
+	--whitespace)
+		shift
+		git_am_opt="$git_am_opt --whitespace=$1"
+		case "$1" in
+		fix|strip)
+			force_rebase=t
+			;;
+		esac
+		;;
+	--ignore-whitespace)
 		git_am_opt="$git_am_opt $1"
 		;;
-	-C*)
+	--committer-date-is-author-date|--ignore-date)
 		git_am_opt="$git_am_opt $1"
+		force_rebase=t
 		;;
-	-*)
-		usage
+	-C)
+		shift
+		git_am_opt="$git_am_opt -C$1"
 		;;
-	*)
+	--root)
+		rebase_root=t
+		;;
+	-f|--no-ff)
+		force_rebase=t
+		;;
+	--rerere-autoupdate|--no-rerere-autoupdate)
+		allow_rerere_autoupdate="$1"
+		;;
+	--)
+		shift
 		break
 		;;
 	esac
 	shift
 done
+test $# -gt 2 && usage
 
-# Make sure we do not have .dotest
-if test -z "$do_merge"
+if test -n "$action"
 then
-	if mkdir .dotest
-	then
-		rmdir .dotest
-	else
-		echo >&2 '
-It seems that I cannot create a .dotest directory, and I wonder if you
-are in the middle of patch application or another rebase.  If that is not
-the case, please rm -fr .dotest and run me again.  I am stopping in case
-you still have something valuable there.'
-		exit 1
-	fi
-else
-	if test -d "$dotest"
+	test -z "$in_progress" && die "No rebase in progress?"
+	# Only interactive rebase uses detailed reflog messages
+	if test "$type" = interactive && test "$GIT_REFLOG_ACTION" = rebase
 	then
-		die "previous dotest directory $dotest still exists." \
-			'try git-rebase < --continue | --abort >'
+		GIT_REFLOG_ACTION="rebase -i ($action)"
+		export GIT_REFLOG_ACTION
 	fi
 fi
 
-# The tree must be really really clean.
-git update-index --ignore-submodules --refresh || exit
-diff=$(git diff-index --cached --name-status -r --ignore-submodules HEAD --)
-case "$diff" in
-?*)	echo "cannot rebase: your index is not up-to-date"
-	echo "$diff"
-	exit 1
+case "$action" in
+continue)
+	# Sanity check
+	git rev-parse --verify HEAD >/dev/null ||
+		die "Cannot read HEAD"
+	git update-index --ignore-submodules --refresh &&
+	git diff-files --quiet --ignore-submodules || {
+		echo "You must edit all merge conflicts and then"
+		echo "mark them as resolved using git add"
+		exit 1
+	}
+	read_basic_state
+	run_specific_rebase
+	;;
+skip)
+	output git reset --hard HEAD || exit $?
+	read_basic_state
+	run_specific_rebase
+	;;
+abort)
+	git rerere clear
+	read_basic_state
+	case "$head_name" in
+	refs/*)
+		git symbolic-ref -m "rebase: aborting" HEAD $head_name ||
+		die "Could not move back to $head_name"
+		;;
+	esac
+	output git reset --hard $orig_head
+	rm -r "$state_dir"
+	exit
 	;;
 esac
 
-# The upstream head must be given.  Make sure it is valid.
-upstream_name="$1"
-upstream=`git rev-parse --verify "${upstream_name}^0"` ||
-    die "invalid upstream $upstream_name"
+# Make sure no rebase is in progress
+if test -n "$in_progress"
+then
+	die '
+It seems that there is already a '"${state_dir##*/}"' directory, and
+I wonder if you are in the middle of another rebase.  If that is the
+case, please try
+	git rebase (--continue | --abort | --skip)
+If that is not the case, please
+	rm -fr '"$state_dir"'
+and run me again.  I am stopping in case you still have something
+valuable there.'
+fi
 
-# Make sure the branch to rebase onto is valid.
-onto_name=${newbase-"$upstream_name"}
-onto=$(git rev-parse --verify "${onto_name}^0") || exit
+if test -n "$interactive_rebase"
+then
+	type=interactive
+	state_dir="$merge_dir"
+elif test -n "$do_merge"
+then
+	type=merge
+	state_dir="$merge_dir"
+else
+	type=am
+	state_dir="$apply_dir"
+fi
 
-# If a hook exists, give it a chance to interrupt
-if test -x "$GIT_DIR/hooks/pre-rebase"
+if test -z "$rebase_root"
 then
-	"$GIT_DIR/hooks/pre-rebase" ${1+"$@"} || {
-		echo >&2 "The pre-rebase hook refused to rebase."
-		exit 1
-	}
+	case "$#" in
+	0)
+		if ! upstream_name=$(git rev-parse --symbolic-full-name \
+			--verify -q @{upstream} 2>/dev/null)
+		then
+			. git-parse-remote
+			error_on_missing_default_upstream "rebase" "rebase" \
+				"against" "git rebase <branch>"
+		fi
+		;;
+	*)	upstream_name="$1"
+		shift
+		;;
+	esac
+	upstream=`git rev-parse --verify "${upstream_name}^0"` ||
+	die "invalid upstream $upstream_name"
+	upstream_arg="$upstream_name"
+else
+	test -z "$onto" && die "You must specify --onto when using --root"
+	unset upstream_name
+	unset upstream
+	upstream_arg=--root
 fi
 
+# Make sure the branch to rebase onto is valid.
+onto_name=${onto-"$upstream_name"}
+case "$onto_name" in
+*...*)
+	if	left=${onto_name%...*} right=${onto_name#*...} &&
+		onto=$(git merge-base --all ${left:-HEAD} ${right:-HEAD})
+	then
+		case "$onto" in
+		?*"$LF"?*)
+			die "$onto_name: there are more than one merge bases"
+			;;
+		'')
+			die "$onto_name: there is no merge base"
+			;;
+		esac
+	else
+		die "$onto_name: there is no merge base"
+	fi
+	;;
+*)
+	onto=$(git rev-parse --verify "${onto_name}^0") ||
+	die "Does not point to a valid commit: $onto_name"
+	;;
+esac
+
 # If the branch to rebase is given, that is the branch we will rebase
 # $branch_name -- branch being rebased, or HEAD (already detached)
 # $orig_head -- commit object name of tip of the branch before rebasing
 # $head_name -- refs/heads/<that-branch> or "detached HEAD"
 switch_to=
 case "$#" in
-2)
+1)
 	# Is it "rebase other $branchname" or "rebase other $commit"?
-	branch_name="$2"
-	switch_to="$2"
+	branch_name="$1"
+	switch_to="$1"
 
-	if git show-ref --verify --quiet -- "refs/heads/$2" &&
-	   branch=$(git rev-parse --verify "refs/heads/$2" 2>/dev/null)
+	if git show-ref --verify --quiet -- "refs/heads/$1" &&
+	   orig_head=$(git rev-parse -q --verify "refs/heads/$1")
 	then
-		head_name="refs/heads/$2"
-	elif branch=$(git rev-parse --verify "$2" 2>/dev/null)
+		head_name="refs/heads/$1"
+	elif orig_head=$(git rev-parse -q --verify "$1")
 	then
 		head_name="detached HEAD"
 	else
-		usage
+		die "fatal: no such branch: $1"
 	fi
 	;;
 *)
@@ -341,90 +454,69 @@ case "$#" in
 		head_name="detached HEAD"
 		branch_name=HEAD ;# detached
 	fi
-	branch=$(git rev-parse --verify "${branch_name}^0") || exit
+	orig_head=$(git rev-parse --verify "${branch_name}^0") || exit
 	;;
 esac
-orig_head=$branch
 
-# Now we are rebasing commits $upstream..$branch on top of $onto
+require_clean_work_tree "rebase" "Please commit or stash them."
+
+# Now we are rebasing commits $upstream..$orig_head (or with --root,
+# everything leading up to $orig_head) on top of $onto
 
 # Check if we are already based on $onto with linear history,
-# but this should be done only when upstream and onto are the same.
-mb=$(git merge-base "$onto" "$branch")
-if test "$upstream" = "$onto" && test "$mb" = "$onto" &&
+# but this should be done only when upstream and onto are the same
+# and if this is not an interactive rebase.
+mb=$(git merge-base "$onto" "$orig_head")
+if test "$type" != interactive && test "$upstream" = "$onto" &&
+	test "$mb" = "$onto" &&
 	# linear history?
-	! (git rev-list --parents "$onto".."$branch" | grep " .* ") > /dev/null
+	! (git rev-list --parents "$onto".."$orig_head" | sane_grep " .* ") > /dev/null
 then
-	# Lazily switch to the target branch if needed...
-	test -z "$switch_to" || git checkout "$switch_to"
-	echo >&2 "Current branch $branch_name is up to date."
-	exit 0
+	if test -z "$force_rebase"
+	then
+		# Lazily switch to the target branch if needed...
+		test -z "$switch_to" || git checkout "$switch_to" --
+		say "Current branch $branch_name is up to date."
+		exit 0
+	else
+		say "Current branch $branch_name is up to date, rebase forced."
+	fi
 fi
 
-if test -n "$verbose"
+# If a hook exists, give it a chance to interrupt
+run_pre_rebase_hook "$upstream_arg" "$@"
+
+if test -n "$diffstat"
 then
-	echo "Changes from $mb to $onto:"
+	if test -n "$verbose"
+	then
+		echo "Changes from $mb to $onto:"
+	fi
 	# We want color (if set), but no pager
 	GIT_PAGER='' git diff --stat --summary "$mb" "$onto"
 fi
 
+test "$type" = interactive && run_specific_rebase
+
 # Detach HEAD and reset the tree
-echo "First, rewinding head to replay your work on top of it..."
-git checkout "$onto^0" >/dev/null 2>&1 ||
-	die "could not detach HEAD"
-# git reset --hard "$onto^0"
+say "First, rewinding head to replay your work on top of it..."
+git checkout -q "$onto^0" || die "could not detach HEAD"
+git update-ref ORIG_HEAD $orig_head
 
 # If the $onto is a proper descendant of the tip of the branch, then
-# we just fast forwarded.
-if test "$mb" = "$branch"
+# we just fast-forwarded.
+if test "$mb" = "$orig_head"
 then
-	echo >&2 "Fast-forwarded $branch_name to $onto_name."
+	say "Fast-forwarded $branch_name to $onto_name."
 	move_to_original_branch
 	exit 0
 fi
 
-if test -z "$do_merge"
+if test -n "$rebase_root"
 then
-	git format-patch -k --stdout --full-index --ignore-if-in-upstream \
-		"$upstream..$orig_head" |
-	git am $git_am_opt --rebasing --resolvemsg="$RESOLVEMSG" &&
-	move_to_original_branch
-	ret=$?
-	test 0 != $ret -a -d .dotest &&
-		echo $head_name > .dotest/head-name &&
-		echo $onto > .dotest/onto &&
-		echo $orig_head > .dotest/orig-head
-	exit $ret
+	revisions="$onto..$orig_head"
+else
+	revisions="$upstream..$orig_head"
 fi
 
-# start doing a rebase with git-merge
-# this is rename-aware if the recursive (default) strategy is used
-
-mkdir -p "$dotest"
-echo "$onto" > "$dotest/onto"
-echo "$onto_name" > "$dotest/onto_name"
-prev_head=$orig_head
-echo "$prev_head" > "$dotest/prev_head"
-echo "$orig_head" > "$dotest/orig-head"
-echo "$head_name" > "$dotest/head-name"
-
-msgnum=0
-for cmt in `git rev-list --reverse --no-merges "$upstream..$orig_head"`
-do
-	msgnum=$(($msgnum + 1))
-	echo "$cmt" > "$dotest/cmt.$msgnum"
-done
-
-echo 1 >"$dotest/msgnum"
-echo $msgnum >"$dotest/end"
-
-end=$msgnum
-msgnum=1
-
-while test "$msgnum" -le "$end"
-do
-	call_merge "$msgnum"
-	continue_merge
-done
-
-finish_rb_merge
+run_specific_rebase