I think that must be for the case where someone registers the proxy servlet at the "/" context and then expects to fall back to other servlets/handlers registered at the same context?  I don't think that's really a use case I intended to support for now; this was really just motivated by the need for the NC UI to proxy requests to the classifier, and they are currently doing it in code.

I'd probably lean towards not worrying about that use case until someone actually hits it, but we can try to be more proactive if folks think it's necessary.