ManifoldSuite.TestStatePinging waiting for worker to exit

[Curtis Hovey]

As seen at
    http://reports.vapour.ws/releases/issue/58cbd801749a563b07c67f57

manifold_test.go:121:
    checkExitsWithError(c, w, "state ping failed: .+")
manifold_test.go:219:
    c.Fatal("timed out waiting for worker to exit")
... Error: timed out waiting for worker to exit

[Anastasia (anastasia-macmood)]

The functionality must have been fixed as part of other work since I cannot reproduce this failure locally under stress.