Show usage string for 'git stripspace -h'

Signed-off-by: NJonathan Nieder <jrnieder@gmail.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

builtin-stripspace.c

@@ -73,9 +73,11 @@ int cmd_stripspace(int argc, const char **argv, const char *prefix)
 	struct strbuf buf = STRBUF_INIT;
 	int strip_comments = 0;
 
-	if (argc > 1 && (!strcmp(argv[1], "-s") ||
+	if (argc == 2 && (!strcmp(argv[1], "-s") ||
 				!strcmp(argv[1], "--strip-comments")))
 		strip_comments = 1;
+	else if (argc > 1)
+		usage("git stripspace [-s | --strip-comments] < <stream>");
 
 	if (strbuf_read(&buf, 0, 1024) < 0)
 		die_errno("could not read the input");