[1.7.x] Fixed #20609 -- Added instructions for using AnonymousUser with RequestFactory.

Backport of a39df37049 from master
[1.7.x] Fixed #23629 -- Allowed autodetector to detect changes in Meta.db_table.

Thanks Naddiseo for reporting.

Backport of 5732424bee from master
[1.7.x] Fixed a flake8 warning.

Backport of f6c208d95c from master