Merge branch 'jk/unbreak-am-h' into maint

"git am -h" triggered a BUG().

* jk/unbreak-am-h:
  am: handle "-h" argument earlier

Author: gitster

builtin/am.c

@@ -2311,6 +2311,9 @@ int cmd_am(int argc, const char **argv, const char *prefix)
 		OPT_END()
 	};
 
+	if (argc == 2 && !strcmp(argv[1], "-h"))
+		usage_with_options(usage, options);
+
 	git_config(git_am_config, NULL);
 
 	am_state_init(&state);