setup of test_ipyparallel_executor test is failing on windows on Python 3.8

[jbweston]

See, for example, here

It times out waiting for the string "Engines appear to have started successfully". Perhaps ipcluster changed its output messages (though one would expect that they be the same on all platforms), or something else.

[basnijholt]

It seems to be intermittent because Py36 Windows is passing.

That output string is probably the same.

[jbweston]

If the test failures are intermittent then it reduces the usefulness of the tests, as we are more likely to disregard an actual failure no?