in lookup doesn't work with lists in a When clause

[Matthew Pava]

I have an annotation that worked fine in Django 1.11, but I just discovered that it doesn't work with Django 2.0. The error message reported:
TypeError: unhashable type: 'list'

I have an Order model that has a status and status_date field, and here's the query that worked in the past (simplified):

Order.objects.annotate(
    end_date=Case(
        When(
            status__in=[3, 2],
            then=Cast(F('status_date'), DateField())
        ),
        default=Value(timezone.now().date())
    )
)

Note the list used as the arg in the __in lookup.

My current workaround is to use Q objects with the | operator.

Order.objects.annotate(
    end_date=Case(
        When(
            Q(status=3) | Q(status=2),
            then=Cast(F('status_date'), DateField())
        ),
        default=Value(timezone.now().date())
    )
)

Others may not find that workaround as practical.