variable $session does not exist any more

currently dblog.admin.inc contains a bug at line 279, since variable $session does not exist any more, it should be $_SESSION['dblog_overview_filter'] instead

function dblog_filter_form($form) {
  $filters = dblog_filters();

  $form['filters'] = array(
    '#type' => 'fieldset',
    '#title' => t('Filter log messages'),
    '#theme' => 'dblog_filters',
    '#collapsible' => TRUE,
    '#collapsed' => empty($session), // <-- this variable was suppressed
  );