Silent and unneccesary dependency on commerce_cart

At the moment there is a silent dependency on commerce_cart if you want to display links:

function theme_commerce_checkout_progress_list($variables) {
  
  ...

  // Option to display back pages as links.
  if ($link) {
    // Load the *shopping cart* order. It gets deleted on last page.
    if ($order = commerce_cart_order_load($GLOBALS['user']->uid)) {
      $order_id = $order->order_id;
    }
  }

  ...
}

Either the dependency should be declared in the .info or, better yet, we should wrap this in module_exists(). Along with this, would it not be better to pull the order from the active menu item if we are on the checkout pages?