title: How to force css cache in production with Symfony2 when its content changes
body: <p>In production, when minifying the css (php app/console assetic:dump), the file is re-created but the name don't change.</p>
  
  <p>Thus users browser keep in cache the old version. A workaround is to add after the css name a parameter like ?v=12 to force that cache, but is there another solution? How Symfony generate the css filename? Name that file with its md5 would solve the problem, because when the file change its name would also change.</p>
  
  <pre><code>{% stylesheets filter='cssrewrite,?yui_css'
          'bundles/app/css/style.css'
      %}
          &lt;link rel="stylesheet" type="text/css" media="screen" href="{{ asset_url }}" /&gt;
      {% endstylesheets %}
  </code></pre>
  
  <p>In my source the filename is still the same event after a change in the css :</p>
  
  <pre><code>&lt;link rel="stylesheet" type="text/css" media="screen" href="/css/b3ba425.css" /&gt;
  </code></pre>