Fixed #17796 -- Rolled back [17588] because the fix for the original relatively

corner case (boolean fields under MySQL spatial backend) had a wider scope with
potentially unintended consequences affecting the main MySQL backend and the
required changes wouldn't be appropiate at this point of the 1.4 development
cycle.

Refs #15169.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@17603 bcc190cf-cafb-0310-a4f2-bffc1f526a37