'You should be able to reliably iterate over all the documents
in a given queryset even if there are multiple iterations of it
happening at the same time.'

def test_iteration_within_iteration(self):

    class Data(Document, ):
        pass
    for i in range(300):
        Data().save()
    qs = Data.objects.limit(250)
    for (i, doc) in enumerate(qs):
        for (j, doc2) in enumerate(qs):
            pass
    self.assertEqual(i, 249)
    self.assertEqual(j, 249)
