This allows using a UUIDField primary key along with the JSON session
serializer.

Thanks to Trac alias jamesbeith for the report and Simon Charette
for the initial patch.

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This is a performance optimization and also fixes test errors with the
upcoming merge of contrib tests into tests/. The tests failed on MySQL
because the models with GeometryField were being checked but the
non-GIS MySQL backend didn't know how to handle them.

Backport of 197dd4b8 from master

Backport of 19188826 from master

During the autumn DST change, the template engine would fail to convert
the naive representation of now when USE_TZ = True. Passing now in UTC
eliminates the issue.

Thanks mbertheau and tricoder42.

Refs #23714.

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This reduces the length of rope RequestContext gives users to hang
themselves with.

Thanks Alex Hill for the report and Tim Graham for the review.

Backport of f2c104ad from master.

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Refs #15779. This will allow easier admin URL changes, when needed.
Thanks Simon Charette for the review.

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This significantly improves performance on PyPy. The previous
implementation would generate a new class on every single request,
which is relatively slow.

Backport of 8099d33b from master

This dramatically improves performance on PyPy. The following benchmark:

python -mtimeit -s "from django.utils.functional import allow_lazy; from django.utils.translation import ugettext_lazy; f = allow_lazy(lambda s: s, str)" "f(ugettext_lazy('abc'))"

goes from 390us per loop to 165us.

Backport of 82e0cd15 from master

Report and original patch by Kay Cha.
Backport of 540ca563 from master.

[1.8.x] Revert "Fixed #24075 -- Prevented running post_migrate signals when unapplying initial migrations of contenttypes and auth"

This reverts commit 737d2492.

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This reverts commit 51dc617b.

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Aymeric says, "It was fun to write, but I don't think it's very useful."

Backport of 607af78b from master