Clearer explanation when exception has no message

"No exception supplied" is misleading; actually there is an exception,
but there's no message string.
Fixed documentation of disable_constraint_checking

The docstring and base implementation of disable_constraint_checking do not indicate that a return value is expected for proper behavior.
Added clarification to the docs, pointing out that unique_for_date only considers the date portion of DateTime fields.
Found a mistake in SQL documentation
Fixed #20305 - Added include for polls/static to MANIFEST.in in tutorial.

Thanks monuszko for the report.
Fixed #20274 - Added some clarifying section headings in the test docs.
Fixed #20177 - Corrected docs for django.test.utils.setup_test_environment.

Thanks vlad.london.uk@ for the report.
Remove outdated ForeignKey manager documentation.
Fixed #20354 -- `makemessages` no longer crashes with `UnicodeDecodeError`

Handle the `UnicodeDecodeError` exception, send a warning to `stdout` with the
file name and location, and continue processing other files.
Python 2.5 is not relevant to master.
Fixed inconsistent punctuation in tutorial 5.
Fixed Sphinx error in tutorial 1.
Remove unnecessary check on __set__ parameters.
Fixed #20256 -- Corrected startproject --template help text

Thanks n0nam3 for the patch.
Fixed test failures on MySQL.

Some tests failed when the time zone definitions were loaded in MySQL
and pytz wasn't installed. This setup isn't supported.
Fixed #20025 -- Pointed to a MySQLdb fork for Python 3.

Made a few minor compatibility adjustments.
[py3] Stopped iterating on exceptions. Refs #20025.
Marked tests of BinaryFields as expected failures on MySQL and Python 3.

Current ports of MySQLdb are very buggy in this area.
Added an HTTP status code to Django's WSGI application that was missing (reason unknown).
Marked a test as an expected failure on MySQL and Python 3.2.

This test hits a bug in current ports of MySQLdb.