hook_update_N() to replace "Existing node" panes with Panopoly's "Content item" pane (Drupal)

existing_node_to_content_item.php

/**
 * Convert 'Existing node' panes to 'Content item' panes.
 */
function hook_update_N() {
  // We're going to load the panes directly from the 'panels_pane' table and
  // replace them with the new pane, reusing the same IDs and everything.
  // Don't try this at home, kids!
  $result = db_query("SELECT * FROM {panels_pane} WHERE type = 'node' AND subtype = 'node'");
  $serialized_fields = array('access', 'configuration', 'cache', 'style', 'css', 'extras', 'locks');
  foreach ($result as $pane) {
    // Unserialize all the serialized fields.
    foreach ($serialized_fields as $field) {
      $pane->$field = unserialize($pane->$field);
    }
    // Load the original node, so we can get it's title.
    if ($node = node_load($pane->configuration['nid'])) {
      $pane->type = 'views_panes';
      $pane->subtype = 'panopoly_widgets_general_content-piece_of_content';
      if ($pane->configuration['build_mode'] == 'full') {
        $view_mode = 'subpane';
      } else {
        $view_mode = $pane->configuration['build_mode'];
      }
      $pane->configuration = array(
        'fields_override' => array(
          'field_featured_image' => TRUE,
          'title' => TRUE,
          'created' => TRUE,
          'name' => TRUE,
        ),
        'exposed' => array(
          'title' => $node->title,
          'type' => 'All',
        ),
        'view_settings' => 'nodes',
        'header_type' => 'none',
        'view_mode' => $view_mode,
      );

      drupal_write_record('panels_pane', $pane, array('pid'));
    }
  }
}