Fixed #22073 - Ensure CreateTable operation handles backwards migration correctly when M2M fields are present
Fixed #21908 -- Added example usage for ModelAdmin.get_inline_instances().

Thanks matt at schinckel.net for the suggestion.
Fixed #21986 -- Added some guidelines for database indexes.

Thanks django-issues at colons.co for the suggestion.
Allowed custom querysets when prefetching single valued relations

The original patch for custom prefetches didn't allow usage of custom
queryset for single valued relations (along ForeignKey or OneToOneKey).
Allowing these enables calling performance oriented queryset methods like
select_related or defer/only.

Thanks @akaariai and @timgraham for the reviews. Refs #17001.
Fixed #16727 -- Added protocol-relative URL support to contenttypes.views.shortcut.
Cleaned up a repr() hack that caused problems on Python3.
Fixed typo in internal CharField method
Fixed spelling in model_forms test class names
Fixed #22085 -- Added a feature for setting non-expiring keys as the default.

This feature allows the default `TIMEOUT` Cache argument to be set to `None`,
so that cache instances can set a non-expiring key as the default,
instead of using the default value of 5 minutes.

Previously, this was possible only by passing `None` as an argument to
the set() method of objects of type `BaseCache` (and subtypes).
Added tests for MTI in RunPython.
Fixed #21893 -- ModelState didn't account for MTI parents inherited from abstract models.
Merge pull request #2396 from loic/ticket21893

Fixed #21893 -- ModelState didn't account for MTI parents inherited from abstract models.
Fixed incorrect docstring in cache tests
Fixed three small flake8 violations.
Fixed #7571 -- Fixed parameter matching in include()'d urlpattern

Fixed URL resolving in the case where an outer regex includes an inner
regex and both regexes use positional parameters instead of named
groups, causing the outer regex's parameters to override the inner
regex's.

Modified the regex url resolver so that it will concatenates and then
normalizes, instead of normalizing and then concatenating.
Fixed incorrect docstring in cache tests (take two)

3e25c8ac69ae336102d91f1d2591ab03f3a91e33 was an incomplete
merge of the pull request.

Thanks to @ramast for catching this.
Really hidden warnings in javascript_quote tests

Refs #21725.
Fixed #22206 -- Passed models.TextField.max_length to forms.CharField.maxlength
Fixed #14549 - Removed restriction of single FKs on intermediary tables

Thanks to Loic Bistuer for review. Minor changes to error messages
done by committer.
Fixed #22207 -- Added support for GenericRelation reverse lookups

GenericRelation now supports an optional related_query_name argument.
Setting related_query_name adds a relation from the related object back to
the content type for filtering, ordering and other query operations.

Thanks to Loic Bistuer for spotting a couple of important issues in
his review.