From: martin f. krafft <madduck@debian.org>
Subject: [TopGit PATCH] Allow help/--help/-h to be run outside of a TopGit repo

The user ought to be able to call `tg help` from anywhere in the filesystem,
not just Git repositories, so the help parsing has to happen before the calls
to git git binary.

Debian bug: #501982

Signed-off-by: martin f. krafft <madduck@debian.org>