Merge branch '3.4'

* 3.4:
  Improved the design of the redirection method in the web toolbar
  Mark SemaphoreStore::isSupported() as internal
  [DI] Add ContainerInterface::IGNORE_ON_UNINITIALIZED_REFERENCE
  [FrameworkBundle] Fix form conflict rule
  [Security] add impersonator_user to "User was reloaded" log message
  [DI] Add upgrade note about case insenstive params
  add (pdo|chain) cache (adapter|simple) prune method
  Update NoSuchPropertyException message for writeProperty
  [Routing] added the possibility to define a prefix for all routes of a controller
  [DI] Don't track merged configs when the extension doesn't expose it
  [Cache] Use namespace versioning for backends that dont support clearing by keys
  [VarDumper] add force-collapse/expand + use it for traces

Author: nicolas-grekas

Store/SemaphoreStore.php

@@ -27,6 +27,8 @@ class SemaphoreStore implements StoreInterface
      * Returns whether or not the store is supported.
      *
      * @return bool
+     *
+     * @internal
      */
     public static function isSupported()
     {