help -a: do not unnecessarily look for a repository

Although 'git help -a' actually doesn't need to be run inside a git
repository and uses no repository-specific information, it looks for a git
directory.  On 'git <TAB><TAB>' the bash completion runs 'git help -a' and
unnecessary 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 with the -a option.

Reported by Vincent Danjean through http://bugs.debian.org/539273

Signed-off-by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Signed-off-by: Gerrit Pape <pape@smarden.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin-help.c

@@ -417,9 +417,6 @@ int cmd_help(int argc, const char **argv, const char *prefix)
 	const char *alias;
 	load_command_list("git-", &main_cmds, &other_cmds);
 
-	setup_git_directory_gently(&nongit);
-	git_config(git_help_config, NULL);
-
 	argc = parse_options(argc, argv, prefix, builtin_help_options,
 			builtin_help_usage, 0);
 
@@ -430,6 +427,9 @@ 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();