From: martin f. krafft <madduck@debian.org>
Subject: [TopGit PATCH] ensure we are in the worktree, not .git

Bert Wesarg suggests to check that we are not inside the .git directory before
setting up topgit. Because git rev-parse --git-dir only works in the top .git
dir, not deeper (i.e. inside .git/refs) and will always return "."

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