Thanks Benjamin Bach for the report and initial patch.
This is a security fix; disclosure to follow shortly.
Backport of 8b93b31487d6d3b0fcbbd0498991ea0db9088054 from master
SuspiciousOperations have been differentiated into subclasses, and
are now logged to a 'django.security.*' logger. SuspiciousOperations
that reach django.core.handlers.base.BaseHandler will now return a 400
instead of a 500.
Thanks to tiwoc for the report, and Carl Meyer and Donald Stufft
for review.
