Fixed #22811 -- Allowed setting both the old and new TEST database settings.

An ImproperlyConfigured exception will be raised they mismatch.
Silenced deprecation warnings for refs #22811 and fixed build.
Fixed #22818 -- Clarified you need to cd into the Django clone.

Thanks Josh Parris.
Fixed #22814 -- Allowed ISO-8601 [+-]hh timezone format in parse_datetime
Merge pull request #2804 from AsymmetricVentures/issue22814

Fixed #22814 -- Allowed ISO-8601 [+-]hh timezone format in parse_datetime
Fixed a staticfiles test on Windows.
Fixed #22823 (and partly #22563) - FKs from unmigrated apps breaking state.

Thanks to bendavis78 for the test and diagnostic work.
Fix test breakage from previous state fix
Fixed #22349 -- Added a note clarifying `RawQuerySet` has no `__len__`.

Thanks cdestigter for the report.
Fixed #16087 -- Added ResolverMatch instance to test client response.

Thanks mrmachine for the suggestion.
Fixed #7599 -- Added get_user_permissions to ModelBackend.

Thanks to @gwilson for the report and initial patch.
Thanks to @charettes and @timgraham for reviewing.