only in patch2:
unchanged:
--- a/core/modules/system/src/Tests/Theme/RegistryTest.php
+++ b/core/modules/system/src/Tests/Theme/RegistryTest.php
@@ -34,18 +34,19 @@ function testRaceCondition() {
     // The theme registry is not marked as persistable in case we don't have a
     // proper request.
     \Drupal::request()->setMethod('GET');
-    $cid = 'test_theme_registry';
 
     // Directly instantiate the theme registry, this will cause a base cache
     // entry to be written in __construct().
     $cache = \Drupal::cache();
     $lock_backend = \Drupal::lock();
-    $registry = new ThemeRegistry($cid, $cache, $lock_backend, array('theme_registry'), $this->container->get('module_handler')->isLoaded());
+    $cid = 'theme_registry:runtime:core';
+    $registry = new ThemeRegistry($cache, $lock_backend, array('theme_registry'), $this->container->get('module_handler')->isLoaded());
 
-    $this->assertTrue(\Drupal::cache()->get($cid), 'Cache entry was created.');
+    $this->assertFalse(\Drupal::cache()->get($cid), 'Cache entry was not created by default.');
 
     // Trigger a cache miss for an offset.
     $this->assertTrue($registry->get('theme_test_template_test'), 'Offset was returned correctly from the theme registry.');
+    $this->assertTRUE(\Drupal::cache()->get($cid), 'Cache entry was created.');
     // This will cause the ThemeRegistry class to write an updated version of
     // the cache entry when it is destroyed, usually at the end of the request.
     // Before that happens, manually delete the cache entry we created earlier
@@ -60,7 +61,7 @@ function testRaceCondition() {
     // Create a new instance of the class. Confirm that both the offset
     // requested previously, and one that has not yet been requested are both
     // available.
-    $registry = new ThemeRegistry($cid, $cache, $lock_backend, array('theme_registry'), $this->container->get('module_handler')->isLoaded());
+    $registry = new ThemeRegistry($cache, $lock_backend, array('theme_registry'), $this->container->get('module_handler')->isLoaded());
     $this->assertTrue($registry->get('theme_test_template_test'), 'Offset was returned correctly from the theme registry');
     $this->assertTrue($registry->get('theme_test_template_test_2'), 'Offset was returned correctly from the theme registry');
   }