Comment 0 for bug 1471770

TestPrunes was changed as part of bug bug 1459291 due to intermittent failures, but still fails sometimes.

<http://reports.vapour.ws/releases/2858/job/run-unit-tests-trusty-ppc64el/attempt/3490>

FAIL: txnpruner_test.go:22: com_juju_juju_worker_txnpruner_test.TestPrunes.pN57_github.com_juju_juju_worker_txnpruner_test.TxnPrunerSuite

txnpruner_test.go:38:
    c.Assert(td >= interval, jc.IsTrue, gc.Commentf("td=%s", td))
... obtained bool = false
... td=9.29ms

This failure is on ppc64/gccgo but that may not be a factor beyond that setup hitting timing issues more often.