title: Symfony2 session-flash with if clause in twig isn't working
body: <p>I try to react on a setted session-flash but get always the else-path</p>
  
  <p>Symfony 2.1.3</p>
  
  <p>Controller:</p>
  
  <pre><code>$this-&gt;get('session')-&gt;getFlashBag()-&gt;set('contactActionNoticeError', 'Message not sent');
  </code></pre>
  
  <p>View (tried "old" and new style) But I get <strong>bla2</strong></p>
  
  <pre><code>{% if app.session.flashbag.has("contactActionNoticeError") or app.session.hasFlash("contactActionNoticeError") %}
      bla1
  {% else %}
      bla2
  {% endif %}
  </code></pre>
  
  <p>when showing all flashes with this:</p>
  
  <pre><code>{% for label, flashes in app.session.flashbag.all %}
      {% for flash in flashes %}
          {{ label }} - {{ flash }}
      {% endfor %}
  {% endfor %}
  </code></pre>
  
  <p>I get this:</p>
  
  <pre><code>contactActionNoticeError - Message not sent
  </code></pre>