More complete breadcrumbs for Ubercart checkout

/**
 * Implementation of hook_preprocess_page().
 */
function mymodule_preprocess_page(&$variables) {
  /*
   * This section sets the breadcrumb on the cart pages hierarchically
   * according to the path elements.  A preprocess function is
   * needed instead of drupal_set_breadcrumb() because Ubercart
   * aleady calls drupal_set_breadcrumb() with undesirable results,
   * which also thwarts the menutrails module.
   */
  $menu = menu_get_item();
  if (preg_match('/^cart($|\/)/', $menu['path'])) {
    $crumbs = array(l(t('Home'), '<front>'));
    $paths = array();
    foreach ($menu['map'] as $arg) {
      $paths[] = $arg;
      $crumbs[] = l(ucfirst($arg), implode('/', $paths));
    }
   $variables['breadcrumb'] = theme('breadcrumb', $crumbs);
  }
}