Output I receive when running my tests using django-webtest on Django trunk: https://gist.github.com/treyhunner/5431078
I haven't tracked down the source of the error yet. I may resort to a git bisect on Django to trace down the exact commit where the failure started.
I currently believe this is a django-webtest bug because using the Django test Client works fine for me on Django trunk. This could also be a bug in Django, WebTest, or django-simple-history though.
I reliably reproduce the bug with:
git clone git://github.com/treyhunner/django-simple-history.git cd django-simple-history virtualenv . source bin/activate pip install https://github.com/django/django/tarball/master python setup.py test
The django-webtest tests also fail currently when running against Django trunk. That seems to be an unrelated problem though.