This is useful:
- to force a rollback on the exit of an atomic block without having to
  raise and catch an exception;
- to prevent a rollback after handling an exception manually.

Fix typo

Fixed missing initializations in WSGIRequest. Refs #20619

Thanks to roman for the report.

Add missing preposition in documentation.

uid is now base64 encoded in password reset URLs/views. A backwards compatible
password_reset_confirm view/URL will allow password reset links generated before
this change to continue to work. This view will be removed in Django 1.7.

Thanks jonash for the initial patch and claudep for the review.

Fixed #20462 - Replaced the str() cast introduced in 273dc550 by force_text()

Thanks to noirbizarre for the report and initial patch.

Thanks to Keryn Knight for the report.

Thanks to grzesiof for the report and to loic84 and Alex Gaynor
for the review.

Those methods were only used by `contrib.admin` internally and exclusively
related to `contrib.auth`. Since they were undocumented but used
in the wild the raised deprecation warning point to an also undocumented
alternative that lives in `contrib.auth`.

Also did some PEP8 and other cleanups in the affected modules.

Thanks jimmylam@ for the suggestion.

This is to allow future compatibility with work that is ongoing in the 2013 GSoC.

In Django < 1.6, override_settings restores the settings module that was
active when the override_settings call was executed, not when it was
run. This can make a difference when override_settings is applied to a
class, since it's executed when the module is imported, not when the
test case is run.

In addition, if the settings module for tests is stored alongside the
tests themselves, importing the settings module can trigger an import
of the tests. Since the settings module isn't fully imported yet,
class-level override_settings statements may store a reference to an
incorrect settings module. Eventually this will result in a crash during
test teardown because the settings module restored by override_settings
won't the one that was active during test setup.

While Django should prevent this situation in the future by failing
loudly in such dubious import sequences, that change won't be backported
to 1.5 and 1.4. However, these versions received the "allowed hosts"
patch and they're prone to "AttributeError: 'Settings' object has no
attribute '_original_allowed_hosts'". To mitigate this regression, this
commits stuffs _original_allowed_hosts on a random module instead of the
settings module.

This problem shouldn't occur in Django 1.6, see #20290, but this patch
will be forward-ported for extra safety.

Also tweaked backup variable names for consistency.

Forward port of 02619227 from stable/1.5.x.

Conflicts:
	django/test/utils.py

Thanks to Tim Graham for the report and review.

Thanks to Michal Sládek for the report and initial patch,
and to loic84 for the review.

The code examples should now work correctly.
The `get_context_data` method in the examples was changed when
necessary to adopt a singular style (get context with super(...),
add the extra keys to the dict then return it).

Thanks to Remco Wendt for the initial report and to Tim Graham
for the review.

Thanks naktinis for the report and initial patch.

Fixed #20587 -- Made convert_values handle None values

Fixed #18872 -- Added prefix to FormMixin

Thanks @ibustama for the initial patch and dragonsnaker for opening the
report.

BaseModelFormSet.forms is now a cached property instead of being
populated in the __init__ method. This behaviour also matches an
example in the documentation.
Thanks Thomasz Swiderski for the report and Simon Charette for the
review.