WordPress 2.1 update breaks xmlrpc compliance

The new update returns int instead of string for categoryId, which makes it impossible to use with some desktop clients (in my case ecto).

According to https://www.movabletype.org/mt-static/docs/mtmanual_programmatic.html categoryId has to be returned as string, which was working with 2.0.5.

Could someone please correct this? And maybe even post what we need to change temporarily in the xmlrpc.php to make it work until the next update?

Thanks