Fixed #22359 -- Changing M2M field to blank=True failed on sqlite.
Fixed #22319 -- Fixed migration external dependencies when there are internal dependencies.
Fixed typo in docstring.
Added 1.6.3 release note for refs #22250.
Fixed #21795 -- Made add_preserved_filters account for url prefixes.

Thanks to trac username honyczek for the report. Refs #6903.
Replaced urllib/urlparse imports with from django.utils.six.moves.
Fixed #22362 -- Improved AuthenticationMiddleware assertion message.

Thanks Keryn Knight.
Fixed #22360 -- Fixed two non-deterministic tests in Python 3.4.

The order of admin's changelist filters in the querystring relied on
dict ordering.
Added test to confirm #12583 resolution
Fixed #22327 -- Turned BaseEmailBackend into a context manager

Changed the BaseEmailBackend to allow usage as context manager to open
and close connections.
Added 1.6.3 release note for refs #22256.
Don't copy list for iteration.
Refactor. Stop using memory for list copies.
Merge pull request #2508 from tomwys/patch-1

Don't copy list for iteration.
Merge pull request #2509 from tomwys/patch-2

Refactor. Stop using memory for list copies.
Revert "Merge pull request #2508 from tomwys/patch-1"

This reverts commit c45607e9395ffd05c2cff454fdb55b3ab05dc0e3, reversing
changes made to 9769337ca855f4831c855d6663ff3f688ee1652d.
Added an explanatory comment. Refs #22017
Fixed #22347 -- Unified FileSystemStorage documentation.

Thanks nliberg for the report.
Document removal of GeoDjangoTestSuiteRunner in 1.6 release notes.
Fixed #22218 -- Deprecated django.conf.urls.patterns.

Thanks Carl Meyer for the suggestion and Alex Gaynor and Carl for reviews.