Since we now build in place, pip install
calls setup.py in place which in turn creates
fake_pkg.egg-info. Since in this test the package we are installing is in script.temp_path,
we must tell script to expect temporary
files to be created.
This should make everything "just work" with respect to combinations of
PATH, sys.path, and multiple Python installs. Later we can add a warning
here to help guide users to better understanding.
Pradyun Gedam
Stéphane Bidoul
Chris Hunt