git-am: print fair error message when format detection fails

Avoid git ending with this message:
	"Patch format  is not supported."

With improved error message in the format detection failure case by
Giuseppe Bilotta.

Signed-off-by: Nicolas Sebrecht <ni.s@laposte.net>
Signed-off-by: Brandon Casey <drafnel@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/git-am.sh b/git-am.sh
index dd60f5d..f719f6e 100755 (executable)
--- a/git-am.sh
+++ b/git-am.sh
@@ -268,7 +268,11 @@ split_patches () {
                msgnum=
                ;;
        *)
-               clean_abort "Patch format $patch_format is not supported."
+               if test -n "$parse_patch" ; then
+                       clean_abort "Patch format $patch_format is not supported."
+               else
+                       clean_abort "Patch format detection failed."
+               fi
                ;;
        esac
 }