Flaky test_task_stream_clear_interval

[fjetter]

First observation on OSX https://github.com/dask/distributed/pull/4813/checks?check_run_id=2726554130

    async def test_task_stream_clear_interval(c, s, a, b):
        ts = TaskStream(s, clear_interval=200)
    
        await wait(c.map(inc, range(10)))
        ts.update()
        await asyncio.sleep(0.010)
        await wait(c.map(dec, range(10)))
        ts.update()
    
        assert len(set(map(len, ts.source.data.values()))) == 1
>       assert ts.source.data["name"].count("inc") == 10
E       assert 0 == 10
E         +0
E         -10

[fjetter]

No observation in the last 30days. Closing