'makemigrations fails to merge migrations with no common ancestor.'

def test_makemigrations_no_common_ancestor(self):

    with self.assertRaises(ValueError) as context:
        with self.temporary_migration_module(module='migrations.test_migrations_no_ancestor'):
            call_command('makemigrations', 'migrations', merge=True)
    exception_message = str(context.exception)
    self.assertIn('Could    not    find    common    ancestor    of', exception_message)
    self.assertIn('0002_second', exception_message)
    self.assertIn('0002_conflicting_second', exception_message)
