[RFC/PATCH] rebase: add -x option to record original commit name

[Jay Soffian <jaysoffian@gmail.com>]

It is often more convenient to use rebase --onto than cherry-pick when
relocating a range of commits, as cherry-pick only supports a single commit at a
time.

This commit teaches rebase the "-x" to record the original commit name, in the
same way as cherry-pick's "-x" option.
---

Note that I explictly did not add support for anything but the simple
format-patch + am codepath. I think it's unlikely to want to record the
original commit name in cases where "-m/-p" are needed. 

However, this option might be useful when using "--interactive", but I wanted
to get feedback first as rebase--interactive is a little scarier to patch. :-)

Thoughts?

 Documentation/git-rebase.txt |    5 +++++
 git-am.sh                    |   14 ++++++++++++++
 git-rebase.sh                |    9 +++++++++
 3 files changed, 28 insertions(+), 0 deletions(-)

diff --git a/Documentation/git-rebase.txt b/Documentation/git-rebase.txt
index 823f2a4..2fb0e96 100644
--- a/Documentation/git-rebase.txt
+++ b/Documentation/git-rebase.txt
@@ -315,6 +315,11 @@ which makes little sense.
 	so that the commit marked for squashing comes right after the
 	commit to be modified, and change the action of the moved
 	commit from `pick` to `squash` (or `fixup`).
+
+-x::
+	Append to the original commit message a note that indicates which commit
+	this change originated from, similar to cherry-pick's -x option. This
+	option is not compatible with -m, -p or --interactive.
 +
 This option is only valid when '--interactive' option is used.
 
diff --git a/git-am.sh b/git-am.sh
index c8b9cbb..83805eb 100755
--- a/git-am.sh
+++ b/git-am.sh
@@ -31,6 +31,7 @@ abort           restore the original branch and abort the patching operation.
 committer-date-is-author-date    lie about committer date
 ignore-date     use current timestamp for author date
 rerere-autoupdate update the index with reused conflict resolution if possible
+add-commit-name* (internal use for git-rebase)
 rebasing*       (internal use for git-rebase)"
 
 . git-sh-setup
@@ -296,6 +297,7 @@ git_apply_opt=
 committer_date_is_author_date=
 ignore_date=
 allow_rerere_autoupdate=
+add_commit_name=
 
 while test $# != 0
 do
@@ -347,6 +349,8 @@ do
 		allow_rerere_autoupdate="$1" ;;
 	-q|--quiet)
 		GIT_QUIET=t ;;
+	--add-commit-name)
+		add_commit_name=t ;;
 	--)
 		shift; break ;;
 	*)
@@ -454,6 +458,7 @@ else
 	echo "$keep" >"$dotest/keep"
 	echo "$scissors" >"$dotest/scissors"
 	echo "$no_inbody_headers" >"$dotest/no_inbody_headers"
+	echo "$add_commit_name" > "$dotest/add_commit_name"
 	echo "$GIT_QUIET" >"$dotest/quiet"
 	echo 1 >"$dotest/next"
 	if test -n "$rebasing"
@@ -507,6 +512,10 @@ then
 else
 	no_inbody_headers=
 fi
+if test "$(cat "$dotest/add_commit_name")" = t
+then
+	add_commit_name=t
+fi
 if test "$(cat "$dotest/quiet")" = t
 then
 	GIT_QUIET=t
@@ -630,6 +639,11 @@ do
 		then
 			echo "$ADD_SIGNOFF"
 		fi
+		if test "$add_commit_name" = t
+		then
+			test -z "$commit" && die "Internal error: expecting a commit name."
+			echo "(cherry picked from commit $commit)"
+		fi
 	    } >"$dotest/final-commit"
 	    ;;
 	*)
diff --git a/git-rebase.sh b/git-rebase.sh
index fb4fef7..511599e 100755
--- a/git-rebase.sh
+++ b/git-rebase.sh
@@ -53,6 +53,7 @@ git_am_opt=
 rebase_root=
 force_rebase=
 allow_rerere_autoupdate=
+add_commit_name=
 
 continue_merge () {
 	test -n "$prev_head" || die "prev_head must be defined"
@@ -353,6 +354,10 @@ do
 	--rerere-autoupdate|--no-rerere-autoupdate)
 		allow_rerere_autoupdate="$1"
 		;;
+	-x)
+		git_am_opt="$git_am_opt --add-commit-name"
+		add_commit_name=t
+		;;
 	-*)
 		usage
 		;;
@@ -386,6 +391,10 @@ else
 		die "previous rebase directory $dotest still exists." \
 			'Try git rebase (--continue | --abort | --skip)'
 	fi
+	if test -n "$add_commit_name"
+	then
+		die "-x not compatible with --merge"
+	fi
 fi
 
 # The tree must be really really clean.
-- 
1.7.0.rc1.200.g9c1f9