Optimized an optimise

        # The annotation->tag link is single values and tag->children links is

        # multi-valued. So we have to split the exclude filter in the middle

        # and then optimise the inner query without losing results.

        # and then optimize the inner query without losing results.

        self.assertQuerysetEqual(

            Annotation.objects.exclude(tag__children__name="t2"),

            ['<Annotation: a2>']