Comment 1 for bug 1748372

There seems to be a race here despite the test semantics.
https://github.com/juju/juju/blob/f76c3f61b17770d0c3c965403496ff09f045af26/worker/provisioner/provisioner_test.go#L1897

I could get this to fail reasonably regularly, but by waiting for the desired 3 attempts I had no failures after 1000 runs.