'Test moving an orphan returns an error'

def test_move_orphaned_child_error(self):

    unit_1_key = self.store.create_item(self.user.id, self.course_key, 'vertical', 'unit1').location
    resp = self.client.ajax_post(self.seq2_update_url, data={'children': [unicode(unit_1_key)]})
    self.assertEqual(resp.status_code, 400)
    self.assertIn('Invalid    data,    possibly    caused    by    concurrent    authors', resp.content)
    self.assertListEqual(self.get_item_from_modulestore(self.seq2_usage_key).children, [])
