fix(test): deal with py2 and py3
fix(test): deal with py2 and py3

It ain't pretty, but should do the job.

Related to #514

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