Tests are broken

One of the tests is currently broken:

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FAIL: tests.test_website_hooks.NotifyRelationTest.test_notify_website_relation_with_same_sitenames
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_StringException: Traceback (most recent call last):
  File "/home/jacek/charms/haproxy/hooks/tests/test_website_hooks.py", line 149, in test_notify_website_relation_with_same_sitenames
    self.log.assert_not_called()
  File "/home/jacek/charms/haproxy/.venv/local/lib/python2.7/site-packages/mock/mock.py", line 915, in assert_not_called
    raise AssertionError(msg)
AssertionError: Expected 'log' to not have been called. Called 1 times.

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Ran 102 tests in 0.198s