[PATCH] rebase--interactive: don't enforce valid branch

[Dave Olszewski <cxreg@pobox.com>]

git rebase allows you to specify a non-branch commit-ish as the "branch"
argument, which leaves HEAD detached when it's finished.  This is
occasionally useful, and this patch brings the same functionality to git
rebase ---interactive.

Signed-off-by: Dave Olszewski <cxreg@pobox.com>
---
 git-rebase--interactive.sh    |    2 --
 t/t3404-rebase-interactive.sh |    7 +++++++
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/git-rebase--interactive.sh b/git-rebase--interactive.sh
index 3e4fd14..d047dcb 100755
--- a/git-rebase--interactive.sh
+++ b/git-rebase--interactive.sh
@@ -783,8 +783,6 @@ first and then run 'git rebase --continue' again."
 
 		if test ! -z "$1"
 		then
-			output git show-ref --verify --quiet "refs/heads/$1" ||
-				die "Invalid branchname: $1"
 			output git checkout "$1" ||
 				die "Could not checkout $1"
 		fi
diff --git a/t/t3404-rebase-interactive.sh b/t/t3404-rebase-interactive.sh
index 4e35137..32ffa15 100755
--- a/t/t3404-rebase-interactive.sh
+++ b/t/t3404-rebase-interactive.sh
@@ -553,4 +553,11 @@ test_expect_success 'reword' '
 	git show HEAD~2 | grep "C changed"
 '
 
+test_expect_success 'rebase while detaching HEAD' '
+	grandparent=$(git rev-parse HEAD~2) &&
+	test_tick &&
+	FAKE_LINES="2 1" git rebase -i HEAD~2 HEAD^0 &&
+	test $grandparent = $(git rev-parse HEAD~2)
+'
+
 test_done
-- 
1.7.0.2.213.gd6898.dirty