watcherSuite.SetUpTest timeout acquiring mutex

[Curtis Hovey]

As seen at
    http://reports.vapour.ws/releases/issue/58d9187a749a5635922084f4

watcher_test.go:41:
    s.JujuConnSuite.SetUpTest(c)
/home/ubuntu/juju-core_2.2-beta2/src/github.com/juju/juju/juju/testing/conn.go:410:
    c.Assert(err, jc.ErrorIsNil)
... value *errors.Err = &errors.Err{message:"cannot read controller kontroll", cause:(*errors.Err)(0xc820306550), previous:(*errors.Err)(0xc8205e8d20), file:"github.com/juju/juju/jujuclient/file.go", line:97} ("cannot read controller kontroll: timeout acquiring mutex")
... error stack: