Remove assertion over fetch refspec when explicitly specified
Remove assertion over fetch refspec when explicitly specified

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