`test_aliases_2` flaky?

Failed only on macOS 3.7 in this CI run: https://github.com/dask/distributed/runs/4099410737?check_suite_focus=true

```python
________________________________ test_aliases_2 ________________________________

c =
s =
a =
b =

@gen_cluster(client=True)
async def test_aliases_2(c, s, a, b):
dsk_keys = [
({"x": (inc, 1), "y": "x", "z": "x", "w": (add, "y", "z")}, ["y", "w"]),
({"x": "y", "y": 1}, ["x"]),
({"x": 1, "y": "x", "z": "y", "w": (inc, "z")}, ["w"]),
]
for dsk, keys in dsk_keys:
result = await c.gather(c.get(dsk, keys, sync=False))
> assert list(result) == list(dask.get(dsk, keys))
E assert [2] == [1]
E At index 0 diff: 2 != 1
E Full diff:
E - [1]
E + [2]

distributed/tests/test_client.py:1106: AssertionError
```