[HttpFoundation] Fix wrong assertion in Response test

Author: stloyd

src/Symfony/Component/HttpFoundation/Tests/ResponseTest.php

@@ -374,7 +374,7 @@ public function testPrepareRemovesContentForHeadRequests()
         $response->prepare($request);
 
         $this->assertEquals('', $response->getContent());
-        $this->assertFalse($response->headers->has('Content-Type'));
+        $this->assertTrue($response->headers->has('Content-Type'));
         $this->assertFalse($response->headers->has('Content-Length'));
     }