Base64 --> Base64Serializer - Why?

I recently tried upgrading to the latest nightly build of SOAP (June 20,
2003) from 2.2.  I needed this to support HTTPS over a proxy server.

The problem I had was that it suddenly started using a different SOAP
serializer type for byte[] content (Base64Serializer instead of Base64).
I had to change my server config to add the new serializer
(Base64Serializer).  The problem is that I have existing servers that I
have to support and I can't change their config to add the serializer.
This basically broke backwards compatibility.

Why was this change made?  Also, is there anything I can do to fix it?
Can I force it to use the old serializer?  

Thanks,
Rich