Fix rebase -p --onto

In a rebase with --onto, the correct test for whether we can skip
rewriting a commit is if it is already on top of $ONTO, not $UPSTREAM.
Without --onto, this distinction does not exist and the behavior does
not change.

In a situation with two merged branches on a common base X:

 X---o---o---o---M
  \             /
   x---x---x---x

 Y

if we try to move the branches from their base on X to be based on Y,
so as to get

 X

 Y---o'--o'--o'--M'
  \             /
   x'--x'--x'--x'

then we fail.  The command `git rebase -p --onto Y X M` moves only the
first-parent chain, like so:

 X
  \
   x---x---x---x
                \
 Y---o'--o'--o'--M'

because it mistakenly drops the other branch(es) x---x---x---x from
the TODO file.  This tests and fixes this behavior.

Signed-off-by: Greg Price <price@ksplice.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/git-rebase--interactive.sh b/git-rebase--interactive.sh
index f96d887d23..23ded48322 100755
--- a/git-rebase--interactive.sh
+++ b/git-rebase--interactive.sh
@@ -703,7 +703,7 @@ first and then run 'git rebase --continue' again."
 					preserve=t
 					for p in $(git rev-list --parents -1 $sha1 | cut -d' ' -s -f2-)
 					do
-						if test -f "$REWRITTEN"/$p -a \( $p != $UPSTREAM -o $sha1 = $first_after_upstream \)
+						if test -f "$REWRITTEN"/$p -a \( $p != $ONTO -o $sha1 = $first_after_upstream \)
 						then
 							preserve=f
 						fi