20b1: problems with editable installs

[mgedmin]

I've decided to try running tox on all the Python projects I maintain with virtualenv 20.0.0b1, to check for regressions in the new beta. Three of the projects failed, all on Python 2.7:

• gtimelog (python: No module named gtimelog)
• irclog2html (ImportError: No module named zope.testrunner)
• zodbbrowser (ImportError: No module named zope.testrunner)

Here's how to reproduce the gtimelog issue:

• git clone https://github.com/gtimelog/gtimelog
• virtualenv -p python2.7 /tmp/venv
• /tmp/venv/bin/pip install -e gtimelog --no-deps
• /tmp/venv/bin/python -c 'import gtimelog'

I expect: no output, the import should succeed.

I get

Traceback (most recent call last):
  File "<string>", line 1, in <module>
ImportError: No module named gtimelog

The --no-deps to pip install is there to make the test simpler and faster; I get the same failure if I do a full pip install -e gtimelog.

I'll create a separate bug for the irclog2html/zodbbrowser issue (they're the same issue): #1518.

I'm on Ubuntu 19.10. I installed virtualenv 20.0.0b1 with pipx install --pip-args=--pre using my system Python 3.7. pipx runpip virtualenv list produces

Package            Version 
------------------ --------
appdirs            1.4.3   
filelock           3.0.12  
importlib-metadata 1.5.0   
pip                20.0.2  
pkg-resources      0.0.0   
setuptools         45.1.0  
six                1.14.0  
virtualenv         20.0.0b1
wheel              0.34.1  
zipp               2.1.0   

[mgedmin]

One difference between virtualenv-created-with-20b1 and virtualenv-created-with-15 appears to be in sys.path: the working virtualenv has ~/src/gtimelog/src in it, the non-working one doesn't.

They both have identical easy-install.pth files in site-packages, and they both have identical gtimelog.egg-link files.

Could it be that the core problem with both this and #1518 is that *.pth files are not processed in the virtualenv's site-packages directory in virtualenvs created with 20b1 on Python 2.7?

[gaborbernat]

@mgedmin we no longer ship our own site.py but rather use the host site.py, so in theory, it well could be that Ubuntu decided to not honour pth files in their site.py which causes the issue. This also explains why I can't reproduce this on macOS.

[gaborbernat]

I think #1521 solves this. Please can you validate?

[mgedmin]

Yes, #1521 fixes this.