[Pytest-commit] Issue #308: Pip version 8 incompatibility (--download-cache option removed) (hpk42/tox)

[Waylan Limberg]

New issue 308: Pip version 8 incompatibility (--download-cache option removed)
https://bitbucket.org/hpk42/tox/issues/308/pip-version-8-incompatibility-download

Waylan Limberg:

When using tox version 2.3.1 and pip version 8.x I get the following [error][1] when tox attempts to install my "deps" (`deps = -rtest-requirements.txt`).

     no such option: --download-cache

    ERROR: could not install deps [-rtest-requirements.txt]; v = InvocationError('/home/travis/build/waylan/Python-Markdown/.tox/py27/bin/pip install --download-cache=/home/travis/build/waylan/Python-Markdown/.tox/cache -rtest-requirements.txt (see /home/travis/build/waylan/Python-Markdown/.tox/py27/log/py27-1.log)', 2)

It is clear that tox is calling `pip install`  with the `--download-cache` flag, which was deprecated in pip version 6.0 and removed in 8.0 (see [release notes][2]). Interestingly, after seeing the error on Travis, I tested on my local machine by first upgrading pip to version 8 before upgradting tox and on tox version 2.2.1 no error was raised with pip version 8. However, once I upgraded tox to 2.3.1 the error appeared.

[1]: https://travis-ci.org/waylan/Python-Markdown/jobs/98800386#L207
[2]: https://pip.pypa.io/en/latest/news/