Fix expr usage for FreeBSD

Some implementations of "expr" (e.g. FreeBSD's) fail, if an
argument starts with a dash.

Signed-off-by: Dennis Stosberg <dennis@stosberg.net>
Signed-off-by: Junio C Hamano <junkio@cox.net>

1 files changed, 1 insertions, 1 deletions

diff --git a/git-am.sh b/git-am.sh
index 4232e27411..679045a540 100755
--- a/git-am.sh
+++ b/git-am.sh
@@ -97,7 +97,7 @@ while case "$#" in 0) break;; esac
 do
 	case "$1" in
 	-d=*|--d=*|--do=*|--dot=*|--dote=*|--dotes=*|--dotest=*)
-	dotest=`expr "$1" : '-[^=]*=\(.*\)'`; shift ;;
+	dotest=`expr "z$1" : 'z-[^=]*=\(.*\)'`; shift ;;
 	-d|--d|--do|--dot|--dote|--dotes|--dotest)
 	case "$#" in 1) usage ;; esac; shift
 	dotest="$1"; shift;;