This commit updates all tests to enforce the Python3 executable. This is
necessary because the `assertRegex` function we use was renamed to this
name only in Python 3.2 [1]
For reference:
s;/usr/bin/env python;/usr/bin/env python3;g
[1]: https://docs.python.org/3/library/unittest.html#unittest.TestCase.assertRegex
- "./run_all --fast" parallelizes all Python tests. Perl and C++ tests
are not guaranteed to run in an isolated environment, so run them
serially instead.
- Adjust some tests in order to recognize them as Python.
