Merge branch '2.8' into 3.1

* 2.8:
  [Validator][GroupSequence] fixed GroupSequence validation ignores PropertyMetadata of parent classes
  [FrameworkBundle][Security] Remove useless mocks
  [DoctrineBridge] Enhance exception message in EntityUserProvider
  added friendly exception when constraint validator does not exist or it is not enabled
  remove duplicate instruction
  [FrameworkBundle] Remove TranslatorBagInterface check
  [FrameworkBundle] Remove duplicated code in RouterDebugCommand
  [Validator] fixed duplicate constraints with parent class interfaces
  SecurityBundle:BasicAuthenticationListener: removed a default argument on getting a header value

Author: nicolas-grekas

Tests/Iterator/MockSplFileInfo.php

@@ -95,12 +95,10 @@ public function setType($type)
         if (is_string($type)) {
             switch ($type) {
                 case 'directory':
-                    $this->type = self::TYPE_DIRECTORY;
                 case 'd':
                     $this->type = self::TYPE_DIRECTORY;
                     break;
                 case 'file':
-                    $this->type = self::TYPE_FILE;
                 case 'f':
                     $this->type = self::TYPE_FILE;
                     break;