Paginator UnorderedObjectListWarning on union(all=True) of two sorted queries

[Rich Rauenzahn]

I wonder if this is a case you want to catch and *not* warn about.

In my case, I'm doing this:

haves = MyModel.objects.filter(foreign_relationship=4).order_by('foreign_relationship__value', 'common_key')
havenots = MyModel.objects.exclude(id__in=haves).order_by('common_key')
query = haves.union(havenots, all=True)

I'm using this with a Paginator. The Paginator complains the queries are not ordered, but they actually are (right?) due to the all=True in the union.

Is this a case the warning ought to handle and ignore?

The Django 1.11 source is:

    def _check_object_list_is_ordered(self):
        """
        Warn if self.object_list is unordered (typically a QuerySet).
        """
        ordered = getattr(self.object_list, 'ordered', None)
        if ordered is not None and not ordered:
            obj_list_repr = (
                '{} {}'.format(self.object_list.model, self.object_list.__class__.__name__)
                if hasattr(self.object_list, 'model')
                else '{!r}'.format(self.object_list)
            )
            warnings.warn(
                'Pagination may yield inconsistent results with an unordered '
                'object_list: {}.'.format(obj_list_repr),
                UnorderedObjectListWarning,
                stacklevel=3
            )

Should union(..., all=True) set ordered in the QuerySet? Or maybe should it look and see if all the source queries are ordered and propagate that to the QuerySet union returns?