diff --git a/core/modules/book/book.module b/core/modules/book/book.module
index e80b5e3..355fd02 100644
--- a/core/modules/book/book.module
+++ b/core/modules/book/book.module
@@ -468,7 +468,9 @@ function template_preprocess_book_export_html(&$variables) {
   $variables['base_url'] = $base_url;
   $variables['language'] = $language_interface;
   $variables['language_rtl'] = ($language_interface->getDirection() == LanguageInterface::DIRECTION_RTL);
-  $variables['head'] = drupal_get_html_head();
+  // @todo: Commenting out the following line is wrong.
+  // @see https://www.drupal.org/node/2477223
+//  $variables['head'] = drupal_get_html_head();
 
   // HTML element attributes.
   $attributes = array();
diff --git a/core/modules/system/src/Tests/Common/AddFeedTest.php b/core/modules/system/src/Tests/Common/AddFeedTest.php
index a83f41b..7ec728e 100644
--- a/core/modules/system/src/Tests/Common/AddFeedTest.php
+++ b/core/modules/system/src/Tests/Common/AddFeedTest.php
@@ -61,9 +61,15 @@ function testBasicFeedAddNoTitle() {
       $build['#attached']['feed'][] = [$feed_info['url'], $feed_info['title']];
     }
 
-    drupal_process_attached($build);
+    // Use the bare HTML page renderer to render our links.
+    $renderer = $this->container->get('bare_html_page_renderer');
+    $response = $renderer->renderBarePage(
+      $build, '', $this->container->get('theme.manager')->getActiveTheme()->getName()
+    );
 
-    $this->setRawContent(drupal_get_html_head());
+    // Glean the content from the response object.
+    $this->setRawContent($response->getContent());
+    // Assert that the content contains the RSS links we specified.
     foreach ($urls as $description => $feed_info) {
       $this->assertPattern($this->urlToRSSLinkPattern($feed_info['url'], $feed_info['title']), format_string('Found correct feed header for %description', array('%description' => $description)));
     }