Hmm, i'm not really into this, so it is as simple as exchanging the XMLSerializer with the 2.1.5 version before building, or are there other dependencies?
We have two different XML serializers. IIRC we changed the the default implementation recently. All you need to do is to use the old implementation. (change it in the cocoon.xconf) Although it has other issues. (Why the heck are you using tabs anyway?)
cheers -- Torsten
