/**
  * Fetch the html code to display the field value in artifact in read only mode
  *
  * @param Tracker_Artifact                $artifact The artifact
  * @param Tracker_Artifact_ChangesetValue $value    The actual value of the field
  *
  * @return string
  */
 public function fetchArtifactValueReadOnly(Tracker_Artifact $artifact, Tracker_Artifact_ChangesetValue $value = null)
 {
     $purifier = Codendi_HTMLPurifier::instance();
     if ($artifact->wasLastModifiedByAnonymous()) {
         $label = $purifier->purify($artifact->getLastModifiedBy());
     } else {
         $value = new Tracker_FormElement_Field_List_Bind_UsersValue($artifact->getLastModifiedBy());
         $label = $purifier->purify($value->getLabel());
     }
     return $label;
 }