Don't assign default value to varaibles passed by reference

CRM/Core/BAO/CustomValue.php:

function getField(&$isBool = null) {

The & gave me a parse error. Assigning defaults to varaiables by reference
is not allowed (at least with php4).

$cf =& new CRM_Core_BAO_CustomField();
$cf->id = $this->custom_field_id;

if (! $cf->find(true))

$isBool = $cf->data_type == Boolean ? true : false;
return $this->typeToField($cf->data_type);
}

I used civicrm-drupal-php4-rev2040.tgz