Bundle config: On or off?

This looks like:
* After installation this module does not change anything
* Check bundles on the settings page to switch off revisions
(so remember to do that after creating new bundles)

/**
 * Implements hook_field_storage_write().
 *
 * @see field_sql_storage_field_storage_write()
 */
function field_sql_norevisions_field_storage_write($entity_type, $entity, $op, $fields) {
  $enabled_entity_bundles = variable_get('field_sql_norevisions_entities', array());
  list($id, $vid, $bundle) = entity_extract_ids($entity_type, $entity);

  if (empty($enabled_entity_bundles[$entity_type][$bundle])) {
    // We fall back to normal Field SQL storage function.
    field_sql_storage_field_storage_write($entity_type, $entity, $op, $fields);
    return;
  }