Fixed #21499 -- Added a paragraph to the docs.
Fixed #21512 -- Added more complete information about Pillow and PIL in model_fields and model_forms tests.
Use str.isupper() to test if a string is uppercased.
Fixed #21355 -- try importing _imaging from PIL namespace first.
Fixed #21448 -- Fixed test client logout with cookie-based sessions

Thanks Gunnar Scherf for the report and the suggested patch.
Fixed a typo in the documentation
Replace use of dict.has_key with `key in dict`
Merge pull request #1985 from raphaa/21499

Fixed #21499 -- Migrations won't work if field signature changes
Fix squashed migration loading ordering issue
Change initial migration writing to work as docs suggest.

Application template now includes an empty migrations module, and
the autodetector will only make initial migrations for apps with
empty modules.
Add gis deconstruct() method (this does not make schema work)
PostGIS schema editor support