Book breadcrumbs are broken

$page was removed from hook_node_view(), but the book module still does:

function book_node_view($node, $teaser, $page) {
  if (!$teaser) {
    if (!empty($node->book['bid']) && $node->build_mode == NODE_BUILD_NORMAL) {
      $node->content['book_navigation'] = array(
        '#markup' => theme('book_navigation', $node->book),
        '#weight' => 100,
      );

      if ($page) {
        menu_set_active_trail(book_build_active_trail($node->book));
        menu_set_active_menu_name($node->book['menu_name']);
      }
    }
  }

  book_node_view_link($node, $teaser, $page);
}

I basically means that the book breadcrumbs are currently broken. We haven't seen that because they are not tested.