Merge branch '4.2'

* 4.2: (26 commits)
  Apply php-cs-fixer rule for array_key_exists()
  [Cache] fix warming up cache.system and apcu
  [Security] Change FormAuthenticator if condition
  handles multi-byte characters in autocomplete
  speed up tests running them without debug flag
  [Translations] added missing Croatian validators
  Fix getItems() performance issue with RedisCluster (php-redis)
  [VarDumper] Keep a ref to objects to ensure their handle cannot be reused while cloning
  IntegerType: reject submitted non-integer numbers
  be keen to newcomers
  [HttpKernel] Fix possible infinite loop of exceptions
  fixed CS
  [Validator] Added missing translations for Afrikaans
  do not validate non-submitted form fields in PATCH requests
  Update usage example in ArrayInput doc block.
  [Console] Prevent ArgvInput::getFirstArgument() from returning an option value
  [Validator] Fixed duplicate UUID
  fixed CS
  [EventDispatcher] Fix unknown priority
  Avoid mutating the Finder when building the iterator
  ...

Author: nicolas-grekas

Client.php

@@ -548,7 +548,7 @@ public function back()
     {
         do {
             $request = $this->history->back();
-        } while (array_key_exists(serialize($request), $this->redirects));
+        } while (\array_key_exists(serialize($request), $this->redirects));
 
         return $this->requestFromRequest($request, false);
     }
@@ -562,7 +562,7 @@ public function forward()
     {
         do {
             $request = $this->history->forward();
-        } while (array_key_exists(serialize($request), $this->redirects));
+        } while (\array_key_exists(serialize($request), $this->redirects));
 
         return $this->requestFromRequest($request, false);
     }