hook $form->setDefaults does not work on billing information

See #CRM-9403 for context

You can reproduce this by making this Drupal module:

<?
function civicrm_setDefault_civicrm_buildForm( $formName, &$form ) {
if($formName=='CRM_Contribute_Form_Contribution_Main'||$formName=='CRM_Contribute_Form_Contribution')

{ $form->setDefaults(array('credit_card_number'=>'214125412')); }

return true;
}
?>