view CONTRIBUTING @ 43410:9bab6407c2c9 stable

tests: use venv on Python 3

This test was failing in some Python 3 environments because
`$PYTHON -m virtualenv` was somehow resulting in Python 2
being used. Why, I'm not sure.

Python 3 includes virtualenv in the standard library as the
`venv` module.

This commit changes test-install.t to use `$PYTHON -m venv` on
Python 3 and `$PYTHON -m virtualenv` on Python 2 (if available).

I chose to make some test output duplicated because we can't
have nested conditionals and there is no easy way to express
ORing of hghave checks.

Differential Revision: https://phab.mercurial-scm.org/D7224

Our full contribution guidelines are in our wiki, please see:

https://www.mercurial-scm.org/wiki/ContributingChanges

If you just want a checklist to follow, you can go straight to

https://www.mercurial-scm.org/wiki/ContributingChanges#Submission_checklist

If you can't run the entire testsuite for some reason (it can be
difficult on Windows), please at least run `contrib/check-code.py` on
any files you've modified and run `python contrib/check-commit` on any
commits you've made (for example, `python contrib/check-commit
273ce12ad8f1` will report some style violations on a very old commit).