git-fetch: Usage string clean-up, emit usage string at unrecognized option

Signed-off-by: NFredrik Kuivinen <freku045@student.liu.se>
Signed-off-by: NJunio C Hamano <junkio@cox.net>

git-fetch.sh

 #!/bin/sh
 #
+
+USAGE='<fetch-options> <repository> <refspec>...'
 . git-sh-setup
 . git-parse-remote
 _x40='[0-9a-f][0-9a-f][0-9a-f][0-9a-f][0-9a-f]'
@@ -34,6 +36,9 @@ do
 	-v|--verbose)
 		verbose=Yes
 		;;
+	-*)
+		usage
+		;;
 	*)
 		break
 		;;