tox fails with pip 10
Trying to run tox in a fresh stem workspace (no .tox dir, which contains the virtualenvs) now fails.
Failure output with pip 10:
no such option: --allow-all-external
ERROR: InvocationError: 'path/to/pip install --allow-all-external -e .'Here's a deprecation note from a tox / pip 9 virtualenv:
py27 runtests: commands[0] | pip install --allow-all-external -e .
DEPRECATION: --allow-all-external has been deprecated and will be removed in the future. Due to changes in the repository protocol, it no longer has any effect.With pip 10 (somewhat recently released), this --allow-all-external flag seemingly got removed.
**atagar: I'll have a patch for this shortly! **