[PATCH] Bugfixes for git-rebase

["Lukas Sandström" <lukass@etek.chalmers.se>]

Fix bugs in git-rebase wrt rebasing another branch than
the current HEAD, rebasing with a dirty working dir,
and rebasing a proper decendant of the target branch.

Signed-off-by: Lukas Sandström <lukass@etek.chalmers.se>

---
Without this patch git rebase complains about
"fatal: cannot read mbox" when doing a fast-forward.

 git-rebase.sh |   29 +++++++++++++++++++----------
 1 files changed, 19 insertions(+), 10 deletions(-)

2c0e6289d37461abbadb878b9ca8d2bfe2ca1a1b
diff --git a/git-rebase.sh b/git-rebase.sh
index 638ff0d..1e9ddde 100755
--- a/git-rebase.sh
+++ b/git-rebase.sh
@@ -18,31 +18,30 @@ you still have something valuable there.
 	exit 1
 fi
 
-# The other head is given.  Make sure it is valid.
-other=$(git-rev-parse --verify "$1^0") || exit
-
-# Make sure we have HEAD that is valid.
-head=$(git-rev-parse --verify "HEAD^0") || exit
-
 # The tree must be really really clean.
 git-update-index --refresh || exit
 diff=$(git-diff-index --cached --name-status -r HEAD)
-case "$different" in
+case "$diff" in
 ?*)	echo "$diff"
 	exit 1
 	;;
 esac
 
+# The other head is given.  Make sure it is valid.
+other=$(git-rev-parse --verify "$1^0") || exit
+
+# Make sure the branch to rebase is valid.
+head=$(git-rev-parse --verify "${2:-HEAD^0}") || exit
+
 # If the branch to rebase is given, first switch to it.
 case "$#" in
 2)
 	git-checkout "$2" || exit
 esac
 
-# If the HEAD is a proper descendant of $other, we do not even need
-# to rebase.  Make sure we do not do needless rebase.  In such a
-# case, merge-base should be the same as "$other".
 mb=$(git-merge-base "$other" "$head")
+
+#Check if we're already rebased.
 if test "$mb" = "$other"
 then
 	echo >&2 "Current branch `git-symbolic-ref HEAD` is up to date."
@@ -51,5 +50,15 @@ fi
 
 # Rewind the head to "$other"
 git-reset --hard "$other"
+
+# If the previous HEAD was a proper descendant of $other, we do not even
+# need to rebase.  Make sure we do not do needless rebase.  In such a
+# case, merge-base should be the same as "$head".
+if test "$mb" = "$head"
+then
+	echo >&2 "Fast-forwarded $head to $other."
+	exit 0
+fi
+
 git-format-patch -k --stdout --full-index "$other" ORIG_HEAD |
 git am --binary -3 -k
-- 
0.99.9.GIT