diff --git a/core/lib/Drupal/Core/Template/TwigPhpStorageCache.php b/core/lib/Drupal/Core/Template/TwigPhpStorageCache.php
index b660e72..85abe24 100644
--- a/core/lib/Drupal/Core/Template/TwigPhpStorageCache.php
+++ b/core/lib/Drupal/Core/Template/TwigPhpStorageCache.php
@@ -12,6 +12,13 @@
 
 /**
  * Provides an alternate cache storage for Twig using PhpStorage.
+ *
+ * This class is designed to work on setups with multiple webheads using a local
+ * filesystem for the twig cache. When generating the cache key, a hash value
+ * depending on the enabled extensions is included. This prevents stale
+ * templates from being reused when twig extensions are enabled or disabled.
+ *
+ * @see \Drupal\Core\DependencyInjection\Compiler\TwigExtensionPass
  */
 class TwigPhpStorageCache implements \Twig_CacheInterface {
 
@@ -37,13 +44,6 @@ class TwigPhpStorageCache implements \Twig_CacheInterface {
   protected $templateCacheFilenamePrefix;
 
   /**
-   * Template source cache for when the template cannot be loaded from storage.
-   *
-   * @var array
-   */
-  protected $templateSourceCache = [];
-
-  /**
    * Store cache backend and other information internally.
    *
    * @param \Drupal\Core\Cache\CacheBackendInterface $cache
@@ -72,11 +72,6 @@ protected function storage() {
    * {@inheritdoc}
    */
   public function generateKey($name, $className) {
-    // We override the cache filename in order to avoid issues with not using
-    // shared filesystems. The Twig templates for example rely on available Twig
-    // extensions, so we use the Twig extension hash which varies by extensions
-    // and their mtime.
-    // @see \Drupal\Core\DependencyInjection\Compiler\TwigExtensionPass
     $hash = hash('sha256', $className);
 
     // The first part is what is invalidated.
@@ -94,7 +89,7 @@ public function has($key) {
    * {@inheritdoc}
    */
   public function load($key) {
-    return $this->storage()->load($key);
+    $this->storage()->load($key);
   }
 
   /**
@@ -102,8 +97,6 @@ public function load($key) {
    */
   public function write($key, $content) {
     $this->storage()->save($key, $content);
-    // Store the compiled template in case loading from PhpStorage fails.
-    $this->templateSourceCache[$key] = $content;
     // Save the last mtime.
     $cid = 'twig:' . $key;
     $this->cache->set($cid, REQUEST_TIME);