Thanks Markus Holtermann for review.

Refactored bump_prefix() to avoid infinite loop and allow more than
than 5 subquires by extending the alphabet to use multi-letters.

Thanks john_scott for the report and Markus Holtermann for review.

Thanks to Michael D. Hoyle for the report and Tim Graham for the review.

The migrations autodetector now issues AlterModelOptions operations for
Meta.managed changes instead of DeleteModel + CreateModel.

Thanks iambibhas for the report and Simon and Markus for review.

Thanks welbornprod for report and initial patch.

Refs #24015.

This prevents AppRegistryNotReady errors when unpickling Django
models from an external script.

Thanks kmmbvnr for the report.

A default is no longer required.

Refs #23989.
Forward port of eb632bfb from stable/1.7.x.

(this includes a forward-port of 9189ef43)

This reverts commit 45bd7b3b.

Thanks amarandon for the report.

Thanks adityagupta104 for the report and Tim Graham for the review.

Thanks wkornewald for the report and Markus Holtermann for review.

Thanks andrewbadr for the report and Carl Meyer for the review.