Fixed #23701 -- Removed an unneeded check in collectstatic.

Thanks prathik for the report.
Added stub release notes for 1.7.2.
Fixed #23621 -- Warn for duplicate models when a module is reloaded.

Previously a RuntimeError was raised every time two models clashed
in the app registry. This prevented reloading a module in a REPL;
while it's not recommended to do so, we decided not to forbid this
use-case by turning the error into a warning.

Thanks @dfunckt and Sergey Pashinin for the initial patches.
Improved warning message when reloading models. Refs #23621.

Thanks dfunckt and Tim Graham.
Allowed test from refs #23612 to be run from a directory other than tests.
Fixed flake8 warning.
Made a doctest compatible with Python 2

That test might not always execute, but can be executed when the
parent test label is explicitely given.
Fixed versionchanged indentation in unit-tests.txt.
Fixed #23630 -- Made AlterModelTable rename auto-created M2M tables.

Thanks Naddiseo for the report, Andrew Godwin for guidance,
and Shai Berger for review.
Fixed #23705 -- Removed unnecessary AliasMatch from example Apache config.

Thanks Keryn Knight for the report.
Added missing available app in migrations test case

In some test combinations, having contrib.auth available but not
contrib.contenttypes can produce failures while creating permissions.
Fixed #23444 -- Deprecated django.contrib.admin.helpers.InlineAdminForm.original_content_type_id
Fixed #23702 -- Fixed adding an explicit id field on SQLite.

Thanks gavinwahl for the report.
Fixed #23707 -- Prevented discovery of duplicated tests
Fixed typo in docs/ref/request-response.txt
Fixed #23618 -- Allowed apps with no models to still have migrations

Basically a4737bf6ae reapplied.
Updated gis_migrations tests
Fixed #23652 -- Restored database name after destroying test database

Thanks Bjarkias for the report.
Removed unused import
Fixed versionchanged indentation in topics/testing/advanced.txt.