Bug in git rebase --continue in v1.8.4

Hi,

if I run rebase --continue (e.g. after a conflict resolution), then the rebase always ends with this error message:
	It seems that there is already a rebase-apply directory, and
	I wonder if you are in the middle of another rebase.  If that is the
	case, please try
        	git rebase (--continue | --abort | --skip)
	If that is not the case, please
        	rm -fr "/home/tron/gitRebaseTest/test/.git/rebase-apply"
	and run me again.  I am stopping in case you still have something
	valuable there.

This happens on git v1.8.4 on FreeBSD. It is fine with v1.8.3.4. It seems to be caused by a1549e1049439386b9fd643fae236ad3ba649650, specifically this hunk:
	--- a/git-rebase--am.sh
	+++ b/git-rebase--am.sh
	@@ -7,12 +7,12 @@ case "$action" in
	 continue)
	  git am --resolved --resolvemsg="$resolvemsg" &&
	  move_to_original_branch
	- exit
	+ return
	  ;;
	 skip)
	  git am --skip --resolvemsg="$resolvemsg" &&

Attached is a test script for this problem.

Regards
	Christoph

#! /bin/sh set -eux

git init test cd test

echo a > file git add . git commit -m a

git branch -t test

echo b > file git add . git commit -m b

git checkout test echo c > file git add . git commit -m c

! git rebase git checkout --theirs . git add . git rebase --continue