Caching expiry with pages that have non-ascii characters in url

Dear Sir
I face a problem in caching pages that have special char like arabic (this pages don't cache at all)
but I found a solutions to solve that
I change line 392 in boost.module

 //$parts['path'] = $parts['full_path'] = preg_replace('/^' . preg_quote($b_path, '/') .'/i', '', $parts['path']);
  $parts['path'] = $parts['full_path'] = urldecode(preg_replace('/^' . preg_quote($b_path, '/') .'/i', '', $parts['path']));

now this pages are cached but in cron this pages don't re-cached again just one

can you help me