[RFC PATCH] Teach rebase to rebase even if upstream is up to date with -f

[Sverre Rabbelier <srabbelier@gmail.com>]

Normally, if the current branch is up to date, the rebase is aborted.
However, it may be desirable to allow rebasing even if the current
branch is up to date, when using '-f' in combination with the
'--whitespace=fix' option for example.

Signed-off-by: Sverre Rabbelier <srabbelier@gmail.com>
---

Say I have a bunch of new commits ready to submit to origin, but I want to fix
some whitespace damage, I could do something like this:

$ git checkout master
$ git branch -b rebase-me
$ git reset --hard origin/master
$ git commit --allow-empty "force rebase"
$ git checkout rebase-me
$ git rebase --whitespace=fix master
$ git rebase -i master # kick out the 'force rebase' commit
$ git checkout master
$ git reset --hard rebase-me
$ git branch -d rebase-me

The result would be that all commits in origin/master..master have any
whitespace errors fixed, but it seems a bit clumsy. That is, the need to create
a commit on master so that 'git rebase' won't bail out early makes the whole
process a lot more involved. This patch addresses simplifies the above process
to the following:

$ git rebase -f --whitespace=fix origin/master

That's a reduction of 9 commands, not too bad at all.

No tests included yet, will add them if there is any interest in the patch
from the list, otherwise I'll just keep it around locally :).

 git-rebase.sh |   19 ++++++++++++++-----
 1 files changed, 14 insertions(+), 5 deletions(-)

diff --git a/git-rebase.sh b/git-rebase.sh
index 6d3eddb..55d0f63 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>|--root] [<branch>]'
+USAGE='[--interactive | -i] [-v] [--force-rebase | -f] [--onto <newbase>] [<upstream>|--root] [<branch>]'
 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>
@@ -48,6 +48,7 @@ prec=4
 verbose=
 git_am_opt=
 rebase_root=
+force_rebase=
 
 continue_merge () {
 	test -n "$prev_head" || die "prev_head must be defined"
@@ -300,6 +301,9 @@ do
 		;;
 	--root)
 		rebase_root=t
+    ;;
+  -f|--f|--fo|--for|--forc|force|--force-r|--force-re|--force-reb|--force-reba|--force_rebas|--force-rebase)
+    force_rebase=t
 		;;
 	-*)
 		usage
@@ -419,10 +423,15 @@ if test "$upstream" = "$onto" && test "$mb" = "$onto" &&
 	# linear history?
 	! (git rev-list --parents "$onto".."$branch" | grep " .* ") > /dev/null
 then
-	# Lazily switch to the target branch if needed...
-	test -z "$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"
+		echo >&2 "Current branch $branch_name is up to date."
+		exit 0
+	else
+		echo "Current branch $branch_name is up to date, rebase forced."
+  fi
 fi
 
 if test -n "$verbose"
-- 
1.6.2.rc0.205.g53b19b.dirty