I was able to hit this only running a small subset of Cinder tests, which may narrow things down a bit:
$ tox -epy27 -- --concurrency=25 --regex "(cinder.tests.unit.test_volume|cinder.tests.unit.test_backup)" ... testtools.matchers._impl.MismatchError: 'consistencygroup.create.start' != 'volume.create.end'
I was able to hit this only running a small subset of Cinder tests, which may narrow things down a bit:
$ tox -epy27 -- --concurrency=25 --regex "(cinder. tests.unit. test_volume| cinder. tests.unit. test_backup) " matchers. _impl.MismatchE rror: 'consistencygro up.create. start' != 'volume.create.end'
...
testtools.