blockclone_form_alter causes error on uploads and perhaps elsewhere

When uploading a file, I get in a javascript dialog:

<br> <b>Fatal error</b>:  Cannot pass parameter 1 by reference in <b>/var/www/drupal/modules/upload/upload.module</b> on line <b>893</b><br> 

Block clone appears to be the culprit because it passes $form_id by reference.

function blockclone_form_alter(&$form_id,&$form) {
  if ($form_id == 'block_admin_display') {
    $count = count($form);
    for($i=0;$i<$count;$i++){
      if ($form[$i]['module']) {
        // append clone link
        if ($form[$i]['module']['#value'] != 'blockclone' && $form[$i]['module']['#value'] != 'blockcache')
          $form[$i]['configure']['#value'] .= ' '.t('<a href="!clone_link">clone</a>',
            array('!clone_link' => url('admin/build/block/blockclone_add/'.$form[$i]['module']['#value'].'/'.$form[$i]['delta']['#value'])));
        // append remove link
        elseif ($form[$i]['module']['#value'] != 'blockcache')
          $form[$i]['configure']['#value'] .= ' '.t('<a href="!clone_link">remove clone</a>',
            array('!clone_link' => url('admin/build/block/blockclone_remove/'.$form[$i]['delta']['#value'])));
      }
    }
  }
}