title: How to make SF2/FOSUserBundle ask user for password again upon specific actions?
body: <p>I have this secured admin area under <code>/admin/</code>. Users need to be logged in via an <code>HTTP basic auth</code> (<code>http_basic</code> set to <code>true</code> in <code>security.yml)</code>.</p>
  
  <p>My goal is, for specific action in specific controller, to re-ask user for his username/password. I thought this would be simple but as per my research, it appears it is not.</p>
  
  <p>I have tried to <code>unset</code> both <code>$_SERVER['PHP_AUTH_USER']</code> and <code>$_SERVER['PHP_AUTH_PW']</code> but it seems to have no effect. I also tried to change <code>header</code> to set a <code>401</code> status code but this has not effect either.</p>
  
  <p>How can this be achievable?</p>