Update to Django 1.8 - AttributeError: django.test.TestCase has no attribute 'cls_atomics'

After updating a Django 1.7 project to Django 1.8 and now get errors when I run the tests (that are subclasses of django.test.TestCase).

Traceback (most recent call last):
  File "env\lib\site-packages\django\test\testcases.py", line 962, in tearDownClass
cls._rollback_atomics(cls.cls_atomics)
  AttributeError: type object 'SomeTests' has no attribute 'cls_atomics'

If I debug through the test I can step through all lines without problems, but after the last line the exception is thrown.

This is an example test:

import django
import unittest
from django.test import TestCase
import logging
import sys
from builtins import classmethod, isinstance

class ATestTests(TestCase):

    @classmethod
    def setUpClass(cls):
        django.setup()
        logging.basicConfig(stream=sys.stderr, level=logging.DEBUG)


    def setUp(self):
        self._app = Application(name="a")


    def testtest(self):

        self.assertIsNotNone(self._app)

My environment:

astroid==1.3.4
colorama==0.3.3
defusedxml==0.4.1
Django==1.8
django-extensions==1.5.2
django-filter==0.9.2
djangorestframework==3.0.5
djangorestframework-xml==1.0.1
eight==0.3.0
future==0.11.4
logilab-common==0.63.2
Markdown==2.5.2
pylint==1.4.1
python-dateutil==2.4.1
python-mimeparse==0.1.4
six==1.9.0
xmltodict==0.9.2

How can I fix this?