This needs to be fixed... not only is the logic wrong compared to the docs, but trunk and 2.2 are different regarding what the limits should be... PR 44574 suggests officially removing the limit, which I'm not too sure about but at least right now, if someone were to set it to 128k, httpd would allow it (so basically, there is no limit) so it seems like a "safe" fix...
So what to do? Comments? What I may just do is follow the rec buffer and not allow it to be less that 512, but with no upper limit and keep the default 8192. And of course update the docs as well as add iobuffersize and receivebuffersize to the ProxyPass docs.
