'Regression test for #13902: When using a ManyToMany in list_filter,
results shouldn\'t appear more than once. Basic ManyToMany.'

def test_distinct_for_m2m_in_list_filter(self):

    blues = Genre.objects.create(name='Blues')
    band = Band.objects.create(name='B.B.    King    Review', nr_of_members=11)
    band.genres.add(blues)
    band.genres.add(blues)
    m = BandAdmin(Band, custom_site)
    request = self.factory.get('/band/', data={'genres': blues.pk})
    cl = ChangeList(request, Band, *get_changelist_args(m))
    cl.get_results(request)
    self.assertEqual(cl.result_count, 1)
