Fix broken test.

flocker.node.functional.test_docker.NamespacedDockerClientTests.test_dead_is_removed
was merged broken, since buildbot was reporting statuses incorrectly.
lint
Merge pull request #990 from ClusterHQ/fix-broken-test-FLOC-1028

[FLOC-1028] Fix broken test

Author: @tomprince 
Reviewer: @wallrj
Fixes https://clusterhq.atlassian.net/browse/FLOC-1028