Thanks Andrews Medina for the initial patch.

Fixed a regression introduced in 59a65598.

Deferred models now automatically update only the fields which are
loaded from the db (with .only() or .defer()). In addition, any field
set manually after the load is updated on save.

This patch removes an unconditional float(value) conversion from db
backend default convert_values() method. This can cause problems when
aggregating over character fields for example. In addition, Oracle
and SQLite already return the bare value from their convert_values().

In the long term the converting should be done by fields, and the
fields should then call database backend specific converters when
needed. The current setup is inflexible for 3rd party fields.

Thanks to Merlijn van Deen for the original patch.

Thanks Aymeric Augustin for the review.

The outer query's set of reusable joins (can_reuse) was passed to the
inner query's add_filter call. This was incorrect.

This mix-in is superseded by the @python_2_unicode_compatible decorator.

* Renamed the __unicode__ methods
* Applied the python_2_unicode_compatible decorator
* Removed the StrAndUnicode mix-in that is superseded by
  python_2_unicode_compatible
* Kept the __unicode__ methods in classes that specifically
  test it under Python 2

This doesn't deal with classes that define both __unicode__ and
__str__; the definition of __str__ should be removed first. It
doesn't guarantee that __str__ will return a str (rather than bytes)
under Python 3 either.

These methods actually return unicode.

These classes already have an identical __unicode__ method, which
will be used after an upcoming refactoring.

on Python 3.

Made behavior given None consistent with how non-numerics were handled.
Thanks to ja.geb@me.com for the report.

reraise with second argument to None is not supported.

This allows the test suite to run without errors on Windows.

Corrected to always generate the cache keys from file names with
forward slashes, not backslashes.

Thanks to simonb for the report and the initial patch.

* Using str() when Python 2 expects bytes and Python 3 Unicode
* Fixed reraise-ing syntax
* Fixed slicing of byte strings