Drupal 7 updatedb puts site offline and online

In the Drupal 7 update_7.inc drush puts a site offline and back online:

function drush_update_batch($start) {
  variable_set('maintenance_mode', TRUE);

...
}

...

function drush_update_finished($success, $results, $operations) {
  // Clear the caches in case the data has been updated.
  drupal_flush_all_caches();
  variable_del('maintenance_mode');
}

This is different from the behavior in update_5.inc and update_6.inc.

For consistency, this offline/online code should be removed from update_7.inc