help: Do not unnecessarily look for a repository

Although 'git help' actually doesn't need to be run inside a git
repository and uses no repository-specific information, it looks for a git
directory.  Searching for a git directory can be annoying in auto-mount
environments.  With this commit, 'git help' no longer searches for a
repository when run without any options.

7c3baa9 originally modified 'git help -a' to not require a repository.
This applies the same fix for 'git help'.

Signed-off-by: David Aguilar <davvid@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin-help.c

@@ -427,16 +427,16 @@ int cmd_help(int argc, const char **argv, const char *prefix)
 		return 0;
 	}
 
-	setup_git_directory_gently(&nongit);
-	git_config(git_help_config, NULL);
-
 	if (!argv[0]) {
 		printf("usage: %s\n\n", git_usage_string);
 		list_common_cmds_help();
 		printf("\n%s\n", git_more_info_string);
 		return 0;
 	}
 
+	setup_git_directory_gently(&nongit);
+	git_config(git_help_config, NULL);
+
 	alias = alias_lookup(argv[0]);
 	if (alias && !is_git_command(argv[0])) {
 		printf("`git %s' is aliased to `%s'\n", argv[0], alias);