minor symfony#11362 [2.3][HttpFoundation] Fix wrong assertion in Response test (stloyd)

This PR was merged into the 2.3 branch.

Discussion
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[2.3][HttpFoundation] Fix wrong assertion in Response test

| Q             | A
| ------------- | ---
| Bug fix?      | kinda
| New feature?  | no
| BC breaks?    | no
| Tests pass?   | yes
| License       | MIT

Commits
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3d63f80 [HttpFoundation] Fix wrong assertion in Response test

Author: stof

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'));
     }