This reverts commit 463fe11b due to
restore of relative paths sorting from isort < 4.3.5 in isort 4.3.10.

Backport of b435f829 from master.

Backport of 463fe11b from master.

Backport of d6e5aad5 from master.

There are existing test failures. The incorrect patch was applied
in 1f42f825.

Backport of b39bd0aa from master

Thanks Sjoerd Job Postmus for the report and initial patch.
Thanks Michael Manfre, Tim Graham, and Florian Apolloner for review.

Backport of 25829197 from master

Backport of 5cc6f02f from master.

Backport of fdc4518f from master.

Backport of c34c6d0a from master.

Backport of 44f98f78 from master.

Backport of 5a5c77d5 from master

Backport of 162ae9c9 from master.

Co-Authored-By: Tim Graham <timograham@gmail.com>
Backport of 1ecc0a39 from master.

Backport of b5fe97a3 from master.

There's a bug that causes a test failure in forms_tests:
https://github.com/python-pillow/Pillow/pull/3501/files#r244651761.

Backport of e4a714b2 from master.

Backport of b7dbd5ff from master.

Prior to this change foreign key constraint references could be left pointing
at tables dropped during operations simulating unsupported table alterations
because of an unexpected failure to disable foreign key constraint checks.

SQLite3 does not allow disabling such checks while in a transaction so they
must be disabled beforehand.

Thanks ezaquarii for the report and Carlton and Tim for the review.

Backport of 315357ad from master.

SQLite 3.26 repoints foreign key constraints on table renames even when
foreign_keys pragma is off which breaks every operation that requires
a table rebuild to simulate unsupported ALTER TABLE statements.

The newly introduced legacy_alter_table pragma disables this behavior
and restores the previous schema editor assumptions.

Thanks Florian Apolloner, Christoph Trassl, Chris Lamb for the report and
troubleshooting assistance.

Backport of c8ffdbe5 from master.

Backport of 95011254 from master

Backport of cc4bb110 from master

Backport of 2fd21a18 from master.

Regression in f185d929.
Backport of e7e55059 from master.

Backport of 97cec6f7 from master.

Backport of 8f90593e from master.

Backport of 64174252 from master.

W504 is mutually exclusive with W503 that we follow.

Backport of 58d1e9aa from master.

Backport of 0b3b7c4b
and 92ccc391 from master

Backport of 2e86710d from master

Backport of 7040e638 from master