Fix and re-enable a test that was disabled.
Fix and re-enable a test that was disabled.

Summary: Regex match on error was fixed and test enabled.

Reviewed By: wez

Differential Revision: D6945540

fbshipit-source-id: 05c71852600587d8603fa510444407d102917c0e

wez/watchman,wez/watchman,wez/watchman,facebook/watchman,facebook/watchman,nodakai/watchman,facebook/watchman,nodakai/watchman,wez/watchman,facebook/watchman,wez/watchman,facebook/watchman,facebook/watchman,nodakai/watchman,facebook/watchman,facebook/watchman,nodakai/watchman,nodakai/watchman,wez/watchman,nodakai/watchman,wez/watchman,nodakai/watchman,nodakai/watchman,wez/watchman,wez/watchman,nodakai/watchman,facebook/watchman