title: Symfony -- Twig's trans filter not picking up locale
body: <p>I have verified that if I add the following line to my twig template, it outputs the desired locale:</p>
  
  <pre><code>{{ app.request.locale }}
  </code></pre>
  
  <p>However, the following is outputting in English:</p>
  
  <pre><code>{{ 'String'|trans }}
  </code></pre>
  
  <p>If I force the locale of the trans filter:</p>
  
  <pre><code>{{ 'String'|trans({}, 'messages', 'ja') }}
  </code></pre>
  
  <p>It outputs in the proper translation.  Note that I'm setting the locale using an eventListener:</p>
  
  <pre><code>public function onKernelRequest(GetResponseEvent $event)
  {
      $request = $event-&gt;getRequest();
      $locale = $request-&gt;cookies-&gt;get('_locale') ? $request-&gt;cookies-&gt;get('_locale') : $request-&gt;getPreferredLanguage($this-&gt;availableLanguages);
  
      $request-&gt;setLocale($locale);
  }
  </code></pre>