Improve testing on Gemnasium Python
As per gitlab-org&3233 (comment 440562516)
- the case where
DS_PIP_DEPENDENCY_PATH
is not set isn't tested; see comment- we need a test case for when
PIP_CERT
is explicitly provided; see comment- and
PIP_REQUIREMENTS_FILE
isn't checked either- the test project has a
requirements.txt
, but the cases where it's namedrequires.txt
orrequirements.pip
are not tested