On a Windows7 OS running Python 2.7 and GitPython-0.3.3.RC1 I was following the tutorial and tried to show the repo.untracked_files list (with no untracked files). The statement generated the error:
Exception WindowsError(5, 'Access is denied') in (bound method AutoInterrupt.del of (git.cmd.AutoInterrupt object at 0x0294B5D0)) ignored

If I go to the cmd.py file and issue a time.sleep(0.01) the problem goes away. I did not try to minimize the sleep further.