title: security.yml access_control match query param
body: <p>I want to secure all urls that have the <code>?preview=true</code> query string applied.
  The following unfortunately does not work. I guess the request matcher looks at pathInfo only.</p>
  
  <pre><code># app/config/security.yml
  access_control:
      - { path: (?|&amp;)preview=true, role: ROLE_ADMIN }
  </code></pre>
  
  <p>Any hints are much appreciated. </p>