django error after test teardown

I have been transforming a project from django v1.3 to v1.8. I have solved many issues on the way, but this one I have no clue.

The site runs ok, and all the tests pass, but after the tests something goes wrong.

Could anyone help me out?

user:~/project/web$ python manage.py test

Creating test database for alias 'default'...
..................................
----------------------------------------------------------------------
Ran 34 tests in 32.187s

OK
Destroying test database for alias 'default'...
Traceback (most recent call last):
  File "manage.py", line 25, in <module>
    execute_from_command_line(sys.argv)
  File "/usr/local/lib/python2.7/dist-packages/http://ift.tt/1DMn9aM", line 338, in execute_from_command_line
    utility.execute()
  File "/usr/local/lib/python2.7/dist-packages/http://ift.tt/1DMn9aM", line 330, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/usr/local/lib/python2.7/dist-packages/http://ift.tt/1YjYmHu", line 30, in run_from_argv
    super(Command, self).run_from_argv(argv)
  File "/usr/local/lib/python2.7/dist-packages/http://ift.tt/1DMnbiY", line 393, in run_from_argv
    self.execute(*args, **cmd_options)
  File "/usr/local/lib/python2.7/dist-packages/http://ift.tt/1YjYmHu", line 74, in execute
    super(Command, self).execute(*args, **options)
  File "/usr/local/lib/python2.7/dist-packages/http://ift.tt/1DMnbiY", line 444, in execute
    output = self.handle(*args, **options)
  File "/usr/local/lib/python2.7/dist-packages/http://ift.tt/1YjYmHu", line 90, in handle
    failures = test_runner.run_tests(test_labels)
AttributeError: 'int' object has no attribute 'run_tests'