Merge branch '2.8' into 3.0

* 2.8:
  [HttpKernel] fixed internal subrequests having an if-modified-since-header
  [Security] Fix deprecated usage of DigestAuthenticationEntryPoint::getKey() in DigestAuthenticationListener
  [Validator] Added additional MasterCard range to the CardSchemeValidator
  Make the exception message more clear.
  [Form] fixed bug - name in ButtonBuilder
  [DoctrineBridge] added missing error code for constraint.
  [ClassLoader] Fix declared classes being computed when not needed
  [varDumper] Fix missing usage of ExceptionCaster::$traceArgs

Conflicts:
	src/Symfony/Bridge/Doctrine/Validator/Constraints/UniqueEntityValidator.php
	src/Symfony/Component/ClassLoader/ClassCollectionLoader.php

Author: nicolas-grekas

Fragment/InlineFragmentRenderer.php

@@ -129,6 +129,8 @@ protected function createSubRequest($uri, Request $request)
         }
 
         $server['REMOTE_ADDR'] = '127.0.0.1';
+        unset($server['HTTP_IF_MODIFIED_SINCE']);
+        unset($server['HTTP_IF_NONE_MATCH']);
 
         $subRequest = Request::create($uri, 'get', array(), $cookies, array(), $server);
         if ($request->headers->has('Surrogate-Capability')) {

Tests/Fragment/InlineFragmentRendererTest.php

@@ -197,6 +197,19 @@ public function testESIHeaderIsKeptInSubrequestWithTrustedHeaderDisabled()
 
         Request::setTrustedHeaderName(Request::HEADER_CLIENT_IP, $trustedHeaderName);
     }
+
+    public function testHeadersPossiblyResultingIn304AreNotAssignedToSubrequest()
+    {
+        $expectedSubRequest = Request::create('/');
+        if (Request::getTrustedHeaderName(Request::HEADER_CLIENT_IP)) {
+            $expectedSubRequest->headers->set('x-forwarded-for', array('127.0.0.1'));
+            $expectedSubRequest->server->set('HTTP_X_FORWARDED_FOR', '127.0.0.1');
+        }
+
+        $strategy = new InlineFragmentRenderer($this->getKernelExpectingRequest($expectedSubRequest));
+        $request = Request::create('/', 'GET', array(), array(), array(), array('HTTP_IF_MODIFIED_SINCE' => 'Fri, 01 Jan 2016 00:00:00 GMT', 'HTTP_IF_NONE_MATCH' => '*'));
+        $strategy->render('/', $request);
+    }
 }
 
 class Bar