[py3] str.decode does not exist; str.encode was intended
Fixed two bugs in 59a35208.

* StandardError doesn't exist any more under Python 3.
* Python 2.6 still allows `raise "foo"`.
Fixed a PendingDeprecationWarning in template_tests.
Fixed a test that relied on database exceptions not being wrapped.
Fixed #19926 -- Fixed a link to code example in queries docs

Thanks Randy Salvo for the report.
Merge pull request #858 from intgr/py3kdoc-fix

Fixed a typo in Python 3 porting guide.
Made dateformat tests reactivate original language
use the real path to fix OS X /var/folders vs. /private/var/folders mismatch
Merge pull request #864 from ambv/realmacosxtmp

Fixed two test failures when tmp dirs are below a symlink.

This affects OS X where /var is a symlink to /private/var.
Added a Trac-related item to the release checklist.
1.5 is no longer "UNDER DEVELOPMENT".

Thanks to Bruno Renie for reporting.
Fixed #12823 -- Was already fixed in master, tests added

Also added a little improvement to sql/query.py to get rid of
non-necessary IS NOT NULL check.
Fixed #5241 -- Kept active transalation in LocaleMiddleware.process_response.
Fixed #19937 - Typo in class-based views intro.
Implemented persistent database connections.

Thanks Anssi Kääriäinen and Karen Tracey for their inputs.
Fixed tests broken in 2ee21d9.
Fixed #19929 -- Improved error when MySQL doesn't have TZ definitions.

Thanks tomas_00 for the report.
Fixed #16612 -- Improved has_changed detection for localized field values

Thanks Simon Charette for the review.
Fixed #18898 -- Added tests with a fix for ModelMultipleChoiceField
Fixed #19960 -- Fixed sentence in contrib.auth signals docs

Thanks edd at slipszenko.net for the report.