* Raise a ValueError if you try to assign the wrong type of object.
* Raise a ValueError if you try to assign None to a field not specified with null=True.
* Cache the set value at set time instead of just at lookup time.
This is a slightly backwards-incompatible change; see BackwardsIncompatibleChanges for more details.
git-svn-id: http://code.djangoproject.com/svn/django/trunk@7574 bcc190cf-cafb-0310-a4f2-bffc1f526a37
self-referential and circular relations. A lot of community debugging went into
this fix, so thanks to bmurdock@gmail.com, Marek Kubica, ramiro, Michael
Radziej (the last two giving test cases showing the problem) and James Bennett
(who did the hard work to actually diagnose the true problem and fix it).
git-svn-id: http://code.djangoproject.com/svn/django/trunk@4676 bcc190cf-cafb-0310-a4f2-bffc1f526a37
