This allows us to iremove an inter-command import.

Fixes #19584.

This implies stop storing file path command line arguments in envvars as
a security measure to start relying on with Popen's shell=False instead,
and addition of an 'utils' module.

Thanks kmichel_wgs for the report.

Forward port of ab6ff2e0 from stable/1.5

Thanks amoebob for the report.

If Django was symlinked into site-packages the previous approach to discover
the tests subdirectory would fail. The revised version now always points to
the location of the source and not the import path.

This is needed to make 'python runtests.py' work, otherwise only
'python ./runtests.py' would work.

Thanks to Ramiro Morales for the initial patch.

Tests can run nearly as fast under PostgreSQL and MySQL as under SQLite
with a bit of configuration and the speedup is always a good thing.

Thanks to choongmin for the original patch.

Classes overriding __eq__ need a __hash__ such that equal objects have
the same hash.

Thanks akaariai for the report and regebro for the patch.

Fixed #17919.

Thanks dahool for the report and initial version of the patch.

Fixed #18176 -- Added test for year lookups with year < 1000

Thanks leandron85@ for the suggestion.

Thanks Tomas Ehrlich for the initial test

This function is now the de facto standard function for rendering values in a
template, and is imported by two other built-in template modules. It shouldn't
have a leading underscore.

Avoid polluting the app cache as it causes unrelated test failures.

Refs #19688.

Thanks loic84 for the report.