[PATCH 3/3] rebase: new convenient option to edit a single commit

["Nguyễn Thái Ngọc Duy" <pclouds@gmail.com>]

"git rebase -e XYZ" is basically the same as

EDITOR="sed -i '1s/pick XYZ/edit XYZ/' $@" \
git rebase -i XYZ^

In English, it prepares the todo list for you to edit only commit XYZ
to save your time. The time saving is only significant when you edit a
lot of commits separately.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
---
 Documentation/git-rebase.txt |  4 ++++
 git-rebase--interactive.sh   | 17 ++++++++++++++---
 git-rebase.sh                | 10 ++++++++++
 3 files changed, 28 insertions(+), 3 deletions(-)

diff --git a/Documentation/git-rebase.txt b/Documentation/git-rebase.txt
index 52c3561..b8c263d 100644
--- a/Documentation/git-rebase.txt
+++ b/Documentation/git-rebase.txt
@@ -359,6 +359,10 @@ unless the `--fork-point` option is specified.
 	user edit that list before rebasing.  This mode can also be used to
 	split commits (see SPLITTING COMMITS below).
 
+-e::
+--edit-one::
+	Prepare the todo list to edit only the commit at <upstream>
+
 -p::
 --preserve-merges::
 	Instead of ignoring merges, try to recreate them.
diff --git a/git-rebase--interactive.sh b/git-rebase--interactive.sh
index a1adae8..4762d57 100644
--- a/git-rebase--interactive.sh
+++ b/git-rebase--interactive.sh
@@ -1040,9 +1040,20 @@ fi
 has_action "$todo" ||
 	die_abort "Nothing to do"
 
-cp "$todo" "$todo".backup
-git_sequence_editor "$todo" ||
-	die_abort "Could not execute editor"
+if test -n "$edit_one"
+then
+	edit_one="`git rev-parse --short $edit_one`"
+	sed "1s/pick $edit_one /edit $edit_one /" "$todo" > "$todo.new" ||
+		die_abort "failed to update todo list"
+	grep "^edit $edit_one " "$todo.new" >/dev/null ||
+		die_abort "expected to find 'edit $edit_one' line but did not"
+	mv "$todo.new" "$todo" ||
+		die_abort "failed to update todo list"
+else
+	cp "$todo" "$todo".backup
+	git_sequence_editor "$todo" ||
+		die_abort "Could not execute editor"
+fi
 
 has_action "$todo" ||
 	die_abort "Nothing to do"
diff --git a/git-rebase.sh b/git-rebase.sh
index 33face1..b8b6aa9 100755
--- a/git-rebase.sh
+++ b/git-rebase.sh
@@ -32,6 +32,7 @@ verify             allow pre-rebase hook to run
 rerere-autoupdate  allow rerere to update index with resolved conflicts
 root!              rebase all reachable commits up to the root(s)
 autosquash         move commits that begin with squash!/fixup! under -i
+e,edit-one!        generate todo list to edit this commit
 committer-date-is-author-date! passed to 'git am'
 ignore-date!       passed to 'git am'
 whitespace=!       passed to 'git apply'
@@ -339,6 +340,10 @@ do
 	-NUM=*)
 		NUM="${1#-NUM=}"
 		;;
+	--edit-one)
+		interactive_rebase=explicit
+		edit_one=t
+		;;
 	--)
 		shift
 		break
@@ -463,6 +468,11 @@ then
 		;;
 	*)	upstream_name="$1"
 		shift
+		if test -n "$edit_one"
+		then
+			edit_one="$upstream_name"
+			upstream_name="$upstream_name^"
+		fi
 		;;
 	esac
 	upstream=$(peel_committish "${upstream_name}") ||
-- 
1.9.0.40.gaa8c3ea