bug #16588 Sent out a status text for unknown HTTP headers. (dawehner)

This PR was submitted for the 2.8 branch but it was merged into the 2.3 branch instead (closes #16588).

Discussion
----------

Sent out a status text for unknown HTTP headers.

* The HTTP RFC explains that header('HTTP/1.1 418 ') should be fine, see http://www.w3.org/Protocols/rfc2616/rfc2616-sec6.html#sec6.1
* Apache itself though is broken, see https://gist.github.com/anonymous/a863d7b493c4b09733ec

The fix is to sent out some status text, when we don't know a better text.

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets |
| License       | MIT
| Doc PR        |

Commits
-------

eec6fbc Sent out a status text for unknown HTTP headers.

src/Symfony/Component/HttpFoundation/Response.php

@@ -412,7 +412,7 @@ public function setStatusCode($code, $text = null)
         }
 
         if (null === $text) {
-            $this->statusText = isset(self::$statusTexts[$code]) ? self::$statusTexts[$code] : '';
+            $this->statusText = isset(self::$statusTexts[$code]) ? self::$statusTexts[$code] : 'unknown status';
 
             return $this;
         }

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

@@ -647,7 +647,7 @@ public function getStatusCodeFixtures()
             array('200', null, 'OK'),
             array('200', false, ''),
             array('200', 'foo', 'foo'),
-            array('199', null, ''),
+            array('199', null, 'unknown status'),
             array('199', false, ''),
             array('199', 'foo', 'foo'),
         );