made Cookie stringification more robust

Author: fabpot

src/Symfony/Component/BrowserKit/Cookie.php

@@ -96,7 +96,7 @@ public function __toString()
                 throw new \UnexpectedValueException(sprintf('The cookie expiration time "%s" is not valid.'), $this->expires);
             }
 
-            $cookie .= '; expires='.substr($dateTime->format(self::$dateFormats[0]), 0, -5);
+            $cookie .= '; expires='.str_replace('+0000', '', $dateTime->format(self::$dateFormats[0]));
         }
 
         if ('' !== $this->domain) {

src/Symfony/Component/HttpKernel/DataCollector/RequestDataCollector.php

@@ -304,7 +304,7 @@ private function getCookieHeader($name, $value, $expires, $path, $domain, $secur
                 }
             }
 
-            $cookie .= '; expires='.substr(\DateTime::createFromFormat('U', $expires, new \DateTimeZone('UTC'))->format('D, d-M-Y H:i:s T'), 0, -5);
+            $cookie .= '; expires='.str_replace('+0000', '', \DateTime::createFromFormat('U', $expires, new \DateTimeZone('GMT'))->format('D, d-M-Y H:i:s T'));
         }
 
         if ($domain) {