Post-update hook problems

["Geoffrey Ferrari" <geoffrey.ferrari@googlemail.com>]

I have a public and a private git repository on the same machine, in
the same user's home directory. I want to ensure that when the public
repos is updated, the private repos automatically receives those
updates. Let's just assume that this is a good idea.

So, I've created a post-update hook script and made it executable. The
script is very simple. It 'cd's to the private repos and then does a
git pull. It looks, in essence, like this:

--
#!/bin/sh

cd /user/home/private/repos
git pull

exit 0
--

When I run this script directly, it works fine. (It also works fine
when I run it directly over ssh). However, when I do a git push to the
public repos, (either locally or remotely over ssh) the script is
called but reports back the following error:

--
fatal: Not a git repository: '.'
Failed to find a valid git directory.
--

Can anyone explain why this happens? And how can I make the script
work properly?

With sincere thanks for your help,

Geoffrey Ferrari