Investigate non-deterministic Python 3.6 scheduled parameter test failure

[joshmeek]

https://circleci.com/gh/PrefectHQ/prefect/60188?utm_campaign=vcs-integration-link&utm_medium=referral&utm_source=github-checks-link

=================================== FAILURES ===================================
_______ TestFlowRunMethod.test_flow_dot_run_passes_scheduled_parameters ________

self = <tests.core.test_flow.TestFlowRunMethod object at 0x7f97b853d8d0>

    def test_flow_dot_run_passes_scheduled_parameters(self):
        a = prefect.schedules.clocks.DatesClock(
            [pendulum.now("UTC").add(seconds=0.1)], parameter_defaults=dict(x=1)
        )
        b = prefect.schedules.clocks.DatesClock(
            [pendulum.now("UTC").add(seconds=0.25)], parameter_defaults=dict(x=2)
        )
    
        x = prefect.Parameter("x", default=None, required=False)
        outputs = []
    
        @prefect.task
        def whats_the_param(x):
            outputs.append(x)
    
        with Flow("test", schedule=prefect.schedules.Schedule(clocks=[a, b])) as f:
            whats_the_param(x)
    
        f.run()
    
>       assert outputs == [1, 2]
E       assert [1] == [1, 2]
E         Right contains one more item: 2
E         Full diff:
E         - [1]
E         + [1, 2]

tests/core/test_flow.py:1620: AssertionError