Allow failure of python 2.6
Allow failure of python 2.6

It really is not supported anymore by anyone, so it seems.

gitpython-developers/gitpython,gitpython-developers/GitPython,gitpython-developers/GitPython,jeblair/GitPython,breavo/GitPython,jeblair/GitPython,gitpython-developers/gitpython,breavo/GitPython