Thanks Reinout van Rees for contributing to the patch.

Fixed #27742 -- Reverted "Fixed #24607 -- Serialized natural keys in multi-table inheritance models."

This reverts commit 74a575eb as it causes
unexpected migrations and doesn't seem to be the best solution.

The method customization was removed in 2ca00faa.

Regression in 2f9861d8.

Fixed a failure in the context processors tests when running in
reverse on MySQL due to an extra query after refs #27683.

Thanks Shai Berger and Tim Graham for review.

Prevented queries from reusing trimmed joins.

Thanks Luke Sneeringer for the suggestion.

The test from refs #20368 only runs this block on Python 2.

Thanks Christian Ullrich for the report and review.

Thanks Mariusz Felisiak and Tim Graham for polishing the patch.

Thanks Tim Graham and Nick Pope for review.

Thanks Tim Graham for the review.

Thanks Tim Graham for the review.

Using __str__() and then repr'ing the result looks strange and can lead
to recursive rendering of forms.

Caused by `contrib/auth/backends.py` changes in
cb7bbf97.