[Koha] Worldcat's xISBN Web service, down?

Hello, We have a test failing because of the xISBN service that is not reachable ( http://xisbn.worldcat.org) Anybody has info about it? Should we remove it from Koha? Is it temporary? Their website does not tell anything about it https://www.worldcat.org/affiliate/webservices/xisbn/app.jsp Please let me know in order to adjust or remove the code. Regards, Jonathan