NixOS/nixpkgs — pull request #4796 by teh (2014-11-02 23:33:32+00:00)
Title: Add gitlab and gitlab-shell.

I had to make several adjustments to make it work with nixos:

* Replace relative config file lookups with ENV variable.
* Modify gitlab-shell to not clear then environment when running
pre-receive.
* Modify gitlab-shell to write some environment variables into
the .authorized_keys file to make sure gitlab-shell reads the
correct config file.

The current version requires the user to install the gitlab-shell
package into the systemPackages environment because
/run/current-system/sw/bin/gitlab-shell is hard-coded in the
.authorized_keys file.