commit fd152424ead6868397ea72ad2bcf4f7c94cd756e
Author: Joel Pittet <joel@pittet.ca>
Date:   Thu May 28 08:26:18 2015 -0700

    book

diff --git a/core/modules/book/src/BookManager.php b/core/modules/book/src/BookManager.php
index 03d8a54..787322e 100644
--- a/core/modules/book/src/BookManager.php
+++ b/core/modules/book/src/BookManager.php
@@ -513,10 +513,10 @@ public function build(array $tree) {
       $item = end($items);
       // Add the theme wrapper for outer markup.
       // Allow menu-specific theme overrides.
-      $build['#theme'] = 'book_tree__book_toc_' . $item['link']['bid'];
+      $build['#theme'] = 'book_tree__book_toc_' . $item['original_link']['bid'];
       $build['#items'] = $items;
       // Set cache tag.
-      $build['#cache']['tags'][] = 'config:system.book.' . $item['link']['bid'];
+      $build['#cache']['tags'][] = 'config:system.book.' . $item['original_link']['bid'];
     }
 
     return $build;
@@ -532,8 +532,6 @@ public function build(array $tree) {
    *
    * @return array
    *   The value to use for the #items property of a renderable menu.
-   *
-   * @throws \DomainException
    */
   protected function buildItems(array $tree) {
     $items = [];
diff --git a/core/modules/book/src/BookManagerInterface.php b/core/modules/book/src/BookManagerInterface.php
index e45f4e4..c1ec60d 100644
--- a/core/modules/book/src/BookManagerInterface.php
+++ b/core/modules/book/src/BookManagerInterface.php
@@ -254,6 +254,8 @@ public function deleteFromBook($nid);
    *
    * @return array
    *   A structured array to be rendered by drupal_render().
+   *
+   * @see \Drupal\Core\Menu\MenuLinkTree::build
    */
   public function build(array $tree);