Issue #2218691 by dawehner: Move the current user out of the node API chain in book.

core/modules/book/book.module

@@ -224,8 +224,13 @@ function book_form_node_form_alter(&$form, &$form_state, $form_id) {
  *
  * @todo: Remove this in favor of an entity field.
  */
-function book_node_builder($entity_type, $entity, &$form, &$form_state) {
+function book_node_builder($entity_type, NodeInterface $entity, &$form, &$form_state) {
   $entity->book = $form_state['values']['book'];
+
+  // Always save a revision for non-administrators.
+  if (!empty($entity->book['bid']) && !\Drupal::currentUser()->hasPermission('administer nodes')) {
+    $entity->setNewRevision();
+  }
 }
 
 /**
@@ -447,10 +452,6 @@ function book_node_view(EntityInterface $node, EntityViewDisplayInterface $displ
  * Implements hook_node_presave().
  */
 function book_node_presave(EntityInterface $node) {
-  // Always save a revision for non-administrators.
-  if (!empty($node->book['bid']) && !\Drupal::currentUser()->hasPermission('administer nodes')) {
-    $node->setNewRevision();
-  }
   // Make sure a new node gets a new menu link.
   if ($node->isNew()) {
     $node->book['nid'] = NULL;