git-mergetool: properly handle "git mergetool -- filename"

Like many git commands, git-mergetool allows "--" to signal
the end of option processing.  This adds a missing "shift"
statement so that this is correctly handled.

Signed-off-by: David Aguilar <davvid@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/git-mergetool.sh b/git-mergetool.sh
index 94187c306c..d4078a6aff 100755
--- a/git-mergetool.sh
+++ b/git-mergetool.sh
@@ -296,6 +296,7 @@ do
 	    esac
 	    ;;
 	--)
+	    shift
 	    break
 	    ;;
 	-*)