tox: run setup.py, add 'venv' to run any command
The virtualenv created via tox were missing the scripts from /bin. The
reason is tox was instructed to skip setup.py install (via skipsdist)
since scap did not have any setup script.
Meanwhile, scap has received a setup.py that takes care of installing
Drop skipsdist = True to have tox run 'pip install'
Install scap in develop mode (ease hacking) via usedevelop = True
Indicate tox minimal version is now 1.6 (for usedevelop)
Add a new virtualenv 'venv' to easily run a command in the proper
$ tox -evenv -- scap --help // dump scap help
As a side effect, that fix documentation building which was not able
to find the script to generate their inline help eg:
.. program-output:: ../bin/mw-update-l10n --help
bin/refreshCdbJsonFiles is still not installed. Done via D162.
Reviewers: dduvall, 20after4, thcipriani, Release-Engineering-Team, mmodell, demon
Reviewed By: Release-Engineering-Team, mmodell
Differential Revision: https://phabricator.wikimedia.org/D161