def rename_settings(apps, schema_editor):
    """Rename settings."""
    LocalConfig = apps.get_model('core', 'LocalConfig')
    lc = LocalConfig.objects.first()
    condition = (lc and 'admin' in lc._parameters and 
        'default_domain_quota' in lc._parameters['admin'])
    if condition:
        lc._parameters['admin']['default_mailbox_quota'] = lc._parameters[
            'admin']['default_domain_quota']
        del lc._parameters['admin']['default_domain_quota']
        lc.save(update_fields=['_parameters'])
