def seek(self, offset, whence=os.SEEK_SET):
        raise NotImplementedError, 'PushbackFile is not seekable'
A non-existent flatpage won't be served if the fallback middlware is disabled and should not add a slash
dataset/ETHPy150Open AppScale/appscale/AppServer/lib/grizzled/grizzled/io/__init__.py/PushbackFile.seek--crossover with--dataset/ETHPy150Open AppScale/appscale/AppServer/lib/django-1.5/django/contrib/flatpages/tests/views.py/FlatpageViewAppendSlashTests.test_redirect_fallback_non_existent_flatpage