test_volume_swap fails on the gate

test_volume_swap started to often fail [1] with:

Captured traceback-1:
~~~~~~~~~~~~~~~~~~~~~
    Traceback (most recent call last):
      File "tempest/common/waiters.py", line 202, in wait_for_volume_status
        raise lib_exc.TimeoutException(message)
    tempest.lib.exceptions.TimeoutException: Request timed out
    Details: Volume 5a071400-4b93-4045-aab9-457c7125e9ab failed to reach available status (current in-use) within the required time (196 s).

Logstash tells us that this started between 3-4 of February.

[1] http://logstash.openstack.org/#/dashboard/file/logstash.json?query=message:%5C%22deprecated%5C%22%20AND%20loglevel:%5C%22WARNING%5C%22%20AND%20build_branch:%5C%22master%5C%22