only in patch2:
unchanged:
--- a/core/lib/Drupal/Core/Plugin/Discovery/AnnotatedClassDiscovery.php
+++ b/core/lib/Drupal/Core/Plugin/Discovery/AnnotatedClassDiscovery.php
@@ -46,13 +46,13 @@ public function getDefinitions() {
     // Register the namespace of classes that can be used for annotations.
     AnnotationRegistry::registerAutoloadNamespace('Drupal\Core\Annotation', array(DRUPAL_ROOT . '/core/lib'));
     // Get all PSR-0 namespaces.
-    $namespaces = drupal_classloader()->getNamespaces();
-    foreach ($namespaces as $ns => $namespace_dirs) {
+    $prefixes = drupal_classloader()->getPrefixes();
+    foreach ($prefixes as $ns => $prefix_dirs) {
 
       // OS-Safe directory separators.
       $ns = str_replace('\\', DIRECTORY_SEPARATOR, $ns);
 
-      foreach ($namespace_dirs as $dir) {
+      foreach ($prefix_dirs as $dir) {
         // Check for the pre-determined directory structure to find plugins.
         $prefix = implode(DIRECTORY_SEPARATOR, array(
           $ns,