[1.4.x] Fixed #18979 -- Avoid endless loop caused by "val in PermLookupDict"

Fixed by defining __iter__ which raises TypeError. This was done to
PermWrapper earlier.

Backport of 50d573d2c0b3e17cbf1aa240b03b52e4ad0c32cd
[1.4.x] -- Fixed Python 2.5 compatibility issues
[1.4.X] Fixed #15338 - Documented django.utils.decorators

Backport of d0345b7114 from master
[1.4.X] Fixed #18413 - Noted that a model's files are not deleted when the model is deleted. Thanks lawgon for the report.

Backport of 1c03b23567 from master
[1.4.X] Fixed #19006 - Quoted filenames in Content-Disposition header.

Backport of 234ca6c61d from master
[1.4.X] Fixed #19051 - Fixed Selenium tearDownClass method; thanks glarrain for the report.

Backport of a1a5c0854f from master
Fixed #19072 -- Corrected an external file path in GeoIP docs

Thanks Flavio Curella for the report and the initial patch.
[1.4.X] Fixed #17435 - Clarified that QuerySet.update returns the number of rows matched

Backport of 6d46c740d8 from master
[1.4.x] Fixed #4501 - Documented how to use coverage.py with Django tests.

Thanks krzysiumed for the draft patch.

Backport of 7ef2781ca0ce48872e21dce2f322c9e4106d1cfd from master.
[1.4.X] Fixed #16817 - Added a guide of code coverage to contributing docs.

Thanks Pedro Lima for the draft patch.

Backport of 06f5da3d78 from master
[1.4.X] Fixed #14165 - Documented that TransactionMiddleware only applies to the default database.

Backport of 938ee7cd36 from master
[1.4.X] Fixed #16588 - Warned about field names that conflict with the model API

Backport of dd0cbc6bdc from master
[1.4.X] Fixed #10936 - Noted that using SQLite for development is a good idea

Backport of 470deb5cbb from master
[1.4.X] Fixed #18256 - Added a potential pitfall when upgrading to MySQL 5.5.5

Backport of c870cb48cd from master
[1.4.x] Fixed #18996 - Clarified overriden model methods not called on bulk operations

Backport of 443999a1eeea70e4deebcf31f8f845696be62c3d from master.
[1.4.x] Fixed #19119 -- Corrected default date input formats in docs

Thanks henrik@aisti.fi for the report.
Backport of 10dc4797ea from master.
[1.4.x] Fixed #18881 -- Made the context option in {% trans %} and {% blocktrans %} accept literals wrapped in single quotes. Thanks to lanyjie for the report.
[1.4.X] Fixed #10936 - Tempered recommendation of SQLite - thanks Karen Tracey for the feedback.

Backport of 9190d89829 from master
[1.4.X] Fixed #18548 - Clarified note regarding reusing model instances when form validation fails.

Backport of fd02bcff4a from master
[1.4.x] Fixed a couple links that didn't backport cleanly