[1.0.X] Fixed #6052 -- Worked around a bug in MySQLdb with regards to handling

SafeUnicode (handle SafeString similarly, just to be safe). Based on a patch
from sfllaw.

Backport of r9467 from trunk.


git-svn-id: http://code.djangoproject.com/svn/django/branches/releases/1.0.X@9469 bcc190cf-cafb-0310-a4f2-bffc1f526a37