update tests for missed stack issues
update tests for missed stack issues

ad-m/heroku-buildpack-python,benmurden/heroku-buildpack-python-ember,AltSchool/heroku-buildpack-python,AltSchool/heroku-buildpack-python,benjaminfox/heroku-buildpack-python-geoip,ad-m/heroku-buildpack-python,Scalingo/python-buildpack,benmurden/heroku-buildpack-python-ember,heroku/heroku-buildpack-python,skilljar/heroku-buildpack-python,benjaminfox/heroku-buildpack-python-geoip,Scalingo/python-buildpack,heroku/heroku-buildpack-python