Fixed #16809 -- Forced MySQL to behave like a database. This avoids a problem where queries that do IS NONE checks can return the wrong result the first time they are executed if there is a recently inserted row. Thanks to James Pyrich for the debug work and patch.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@16785 bcc190cf-cafb-0310-a4f2-bffc1f526a37