git-config: don't silently ignore options after --list

Error out if someone gives options after --list since that is
not a valid syntax.

Signed-off-by: Frank Lichtenheld <frank@lichtenheld.de>
Signed-off-by: Lars Hjemli <hjemli@gmail.com>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

builtin-config.c

@@ -172,8 +172,11 @@ int cmd_config(int argc, const char **argv, const char *prefix)
 			type = T_INT;
 		else if (!strcmp(argv[1], "--bool"))
 			type = T_BOOL;
-		else if (!strcmp(argv[1], "--list") || !strcmp(argv[1], "-l"))
+		else if (!strcmp(argv[1], "--list") || !strcmp(argv[1], "-l")) {
+			if (argc != 2)
+				usage(git_config_set_usage);
 			return git_config(show_all_config);
+		}
 		else if (!strcmp(argv[1], "--global")) {
 			char *home = getenv("HOME");
 			if (home) {