function _maybe_update_core() {
  // include an unmodified $wp_version
  include( ABSPATH . WPINC . '/version.php' );

  $current = get_site_transient( 'update_core' );

  if ( isset( $current->last_checked, $current->version_checked ) &&
    12 * HOUR_IN_SECONDS > ( time() - $current->last_checked ) &&
    $current->version_checked == $wp_version ) {
    return;
  }
  wp_version_check();
}