[PATCH] Allow to specify the editor used for git rebase -i by config/environment var

[Peter Oberndorfer <kumbayo84@arcor.de>]

The search order for choosing the sequence editor is:
$GIT_SEQUENCE_EDITOR
git config sequence.editor
git var GIT_EDITOR (default editor for commit messages)

With this change is it possible to have a separate
(possibly graphical) editor that helps the user
during a interactive rebase.

Using $GIT_EDITOR or core.editor config var for this is not possible
since they is also used to start the commit message editor for reword action.

Signed-off-by: Peter Oberndorfer <kumbayo84@arcor.de>
---
I reworded the commit message and the config description a bit.
renamed to sequence.editor / $GIT_SEQUENCE_EDITOR
and moved the helper to git-rebase--interactive.sh

 Documentation/config.txt   |    7 +++++++
 git-rebase--interactive.sh |   15 ++++++++++++++-
 2 files changed, 21 insertions(+), 1 deletions(-)

diff --git a/Documentation/config.txt b/Documentation/config.txt
index 03296b7..048c5f9 100644
--- a/Documentation/config.txt
+++ b/Documentation/config.txt
@@ -473,6 +473,13 @@ core.editor::
 	variable when it is set, and the environment variable
 	`GIT_EDITOR` is not set.  See linkgit:git-var[1].
 
+sequence.editor::
+	Text editor used by git rebase -i for editing the rebase todo file.
+	The value is meant to be interpreted by the shell when it is used.
+	It can be overridden by the 'GIT_SEQUENCE_EDITOR' environment variable.
+	When not configured the default commit message editor is used instead.
+	See linkgit:git-var[1]
+
 core.pager::
 	The command that git will use to paginate output.  Can
 	be overridden with the `GIT_PAGER` environment
diff --git a/git-rebase--interactive.sh b/git-rebase--interactive.sh
index 94f36c2..13a0661 100644
--- a/git-rebase--interactive.sh
+++ b/git-rebase--interactive.sh
@@ -161,6 +161,19 @@ do_with_author () {
 	)
 }
 
+git_sequence_editor() {
+	if test -z "${GIT_SEQUENCE_EDITOR:+set}"
+	then
+		GIT_SEQUENCE_EDITOR="$(git config sequence.editor)"
+		if [ -z "$GIT_SEQUENCE_EDITOR" ]
+		then
+			GIT_SEQUENCE_EDITOR="$(git var GIT_EDITOR)" || return $?
+		fi
+	fi
+
+	eval "$GIT_SEQUENCE_EDITOR" '"$@"'
+}
+
 pick_one () {
 	ff=--ff
 	case "$1" in -n) sha1=$2; ff= ;; *) sha1=$1 ;; esac
@@ -832,7 +845,7 @@ has_action "$todo" ||
 	die_abort "Nothing to do"
 
 cp "$todo" "$todo".backup
-git_editor "$todo" ||
+git_sequence_editor "$todo" ||
 	die_abort "Could not execute editor"
 
 has_action "$todo" ||
-- 
1.7.7.329.g2140c