Testcase 'test_create_continuous_audit_with_wrong_interval' was broken

In the latest zuul results, got broken testcase:

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Failed 1 tests - output below:
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watcher.tests.api.v1.test_audits.TestPost.test_create_continuous_audit_with_wrong_interval
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Captured traceback:
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    Traceback (most recent call last):

      File "/usr/lib/python3.6/unittest/mock.py", line 1183, in patched
    return func(*args, **keywargs)

      File "/home/zuul/src/opendev.org/openstack/watcher/watcher/tests/api/v1/test_audits.py", line 705, in test_create_continuous_audit_with_wrong_interval
    self.assertIn(expected_error_msg, response.json['error_message'])

      File "/home/zuul/src/opendev.org/openstack/watcher/.tox/py36/lib/python3.6/site-packages/testtools/testcase.py", line 421, in assertIn
    self.assertThat(haystack, Contains(needle), message)

      File "/home/zuul/src/opendev.org/openstack/watcher/.tox/py36/lib/python3.6/site-packages/testtools/testcase.py", line 502, in assertThat
    raise mismatch_error

    testtools.matchers._impl.MismatchError: 'Exactly 5 or 6 columns has to be specified for iteratorexpression.' not in '{"faultcode": "Server", "faultstring": "Exactly 5 or 6 columns has to be specified for iterator expression.", "debuginfo": null}'