Merge branch '2.8' into 3.1

* 2.8:
  [HttpKernel] Fix too strict test

Author: nicolas-grekas

Tests/DataCollector/DumpDataCollectorTest.php

@@ -49,11 +49,7 @@ public function testDump()
         );
         $this->assertEquals($xDump, $dump);
 
-        $this->assertStringMatchesFormat(
-            'a:1:{i:0;a:5:{s:4:"data";O:39:"Symfony\Component\VarDumper\Cloner\Data":4:{s:45:"Symfony\Component\VarDumper\Cloner\Datadata";a:1:{i:0;a:1:{i:0;i:123;}}s:49:"Symfony\Component\VarDumper\Cloner\DatamaxDepth";i:%i;s:57:"Symfony\Component\VarDumper\Cloner\DatamaxItemsPerDepth";i:%i;s:54:"Symfony\Component\VarDumper\Cloner\DatauseRefHandles";i:%i;}s:4:"name";s:25:"DumpDataCollectorTest.php";s:4:"file";s:%a',
-            str_replace("\0", '', $collector->serialize())
-        );
-
+        $this->assertStringMatchesFormat('a:1:{i:0;a:5:{s:4:"data";O:39:"Symfony\Component\VarDumper\Cloner\Data":%a', $collector->serialize());
         $this->assertSame(0, $collector->getDumpsCount());
         $this->assertSame('a:0:{}', $collector->serialize());
     }