[PATCH v2 09/23] rebase -i: teach do_pick the option --edit

[Fabian Ruch <bafain@gmail.com>]

`do_pick` is the git-cherry-pick wrapper in git-rebase--interactive
that is used to implement the to-do list command `pick`. To cater for
the different pick behaviours (like `reword`), `do_pick` accepts
several options not only from the git-cherry-pick but also the
git-commit interface. Add the common option `--edit` to let the user
edit the log message of the named commit.

Loop over `$@` to parse the `do_pick` arguments. Assign the local
variable `edit` if one of the options is `--edit` so that the
remainder of `do_pick` can easily check whether the client code asked
to edit the commit message. If one of the options is unknown, mention
it on the console and `die`. Break the loop on the first non-option
and do some sanity checking to ensure that there exactly two
non-options, which are interpreted by the remainder as `<commit>` and
`<title>` like before.

`do_pick` ought to act as a wrapper around `cherry-pick`.
Unfortunately, it cannot just forward `--edit` to the `cherry-pick`
command line. The assembled command line is executed within a command
substitution for controlling the verbosity of `rebase--interactive`.
Passing `--edit` would either hang the terminal or clutter the
substituted command output with control sequences. Execute the
`reword` code from `do_next` instead if the option `--edit` is
specified.

Signed-off-by: Fabian Ruch <bafain@gmail.com>
---
 git-rebase--interactive.sh | 43 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 43 insertions(+)

diff --git a/git-rebase--interactive.sh b/git-rebase--interactive.sh
index edc323d..aed2f93 100644
--- a/git-rebase--interactive.sh
+++ b/git-rebase--interactive.sh
@@ -461,7 +461,42 @@ record_in_rewritten() {
 	esac
 }
 
+# Apply the changes introduced by the given commit to the current head.
+#
+# do_pick [--edit] <commit> <title>
+#
+# Wrapper around git-cherry-pick.
+#
+# -e, --edit
+#     After picking <commit>, open an editor and let the user edit the
+#     commit message. The editor contents becomes the commit message of
+#     the new head. This creates a fresh commit.
+#
+# <commit>
+#     The commit to cherry-pick.
+#
+# <title>
+#     The commit message title of <commit>. Used for information
+#     purposes only.
 do_pick () {
+	edit=
+	while test $# -gt 0
+	do
+		case "$1" in
+		-e|--edit)
+			edit=y
+			;;
+		-*)
+			die "do_pick: unrecognized option -- $1"
+			;;
+		*)
+			break
+			;;
+		esac
+		shift
+	done
+	test $# -ne 2 && die "do_pick: wrong number of arguments"
+
 	if test "$(git rev-parse HEAD)" = "$squash_onto"
 	then
 		# Set the correct commit message and author info on the
@@ -483,6 +518,14 @@ do_pick () {
 		pick_one $1 ||
 			die_with_patch $1 "Could not apply $1... $2"
 	fi
+
+	if test -n "$edit"
+	then
+		output git commit --allow-empty --amend --no-post-rewrite --no-pre-commit ${gpg_sign_opt:+"$gpg_sign_opt"} || {
+			warn "Could not amend commit after successfully picking $1... $2"
+			exit_with_patch $1 1
+		}
+	fi
 }
 
 do_next () {
-- 
2.0.1