'makemigrations exits if in merge mode with no conflicts.'

def test_makemigrations_merge_no_conflict(self):

    out = io.StringIO()
    with self.temporary_migration_module(module='migrations.test_migrations'):
        call_command('makemigrations', merge=True, stdout=out)
    self.assertIn('No    conflicts    detected    to    merge.', out.getvalue())
