Merge branch '4.4' into 5.0

* 4.4: [VarDumper] fix side-effect by not using mt_rand()

Author: fabpot

src/Symfony/Component/VarDumper/Cloner/VarCloner.php

@@ -45,7 +45,7 @@ protected function doClone($var)
  // or null if the original value is used directly
 
  if (!$gid = self::$gid) {
- $gid = self::$gid = uniqid(mt_rand(), true); // Unique string used to detect the special $GLOBALS variable
+ $gid = self::$gid = md5(random_bytes(6)); // Unique string used to detect the special $GLOBALS variable
  }
  $arrayStub = new Stub();
  $arrayStub->type = Stub::TYPE_ARRAY;