Git --file doesn't override $HOME in version 1.8.1.2

Using Ubuntu 13.04 with Git 1.8.1.2 I stumbled upon a problem using Puppet.

In Puppet we launch Git with the command: '/usr/bin/git config --file /home/qt/.gitconfig --get "user.name" "Qt Continuous Integration System"'
However, puppet logs: "fatal: unable to access '/root/.config/git/config': Permission denied".

Puppet is run as root, so HOME points to /root, but still -file should override the environment variable.

If the same command is run directly from terminal as root, it works as well.

With 1.8.3.2 the problem didn't reoccur.

-Tony
-------
Digia, Qt