create virtualenv before running server unit tests

so we can have different dependencies between branches without breaking
tests
2 jobs for feature-s/server_unit_tests in 12 seconds (queued for 1 second)
Status Job ID Name Coverage
  Test Tools
passed #71450
test_tools

00:00:03

 
  Test Unit
failed #71451
web
test_server_unit

00:00:09

 
Name Stage Failure
failed
test_server_unit Test Unit There is an unknown failure, please try again
$ cp -p doc/analysis-example.vidjil browser/
$ virtualenv $CI_BUILD_REF_SLUG
New python executable in /home/gitlab-runner/builds/b8d876c1/0/vidjil/vidjil/feature-s-server-unit-tests/bin/python2
Also creating executable in /home/gitlab-runner/builds/b8d876c1/0/vidjil/vidjil/feature-s-server-unit-tests/bin/python
Installing setuptools, pkg_resources, pip, wheel...done.
Running virtualenv with interpreter /usr/bin/python2
$ pip install -r requirements.txt
bash: line 70: pip: command not found
ERROR: Job failed: exit status 1