I just pushed a few changes to master that get the build working (on 64-bit Debian Linux, no other platforms tested). They're mostly small changes and I hope they won't break anything. This actually gets "make doc" happy again after a good while, so it would be really awesome if I haven't just broken something unrelated :)
There's another, more significant, change that happened in the past few months. It's not a simple fix. The default behaviour of Protocols.DNS.async_host_to_ip, which is used by Protocols.HTTP, changed from "only look up A records" to "look up AAAA and A records, and return the first AAAA if found, otherwise the first A". Unfortunately everything is built to assume that there's at most one IP address for that host name.
The ultimate solution would be to have an asynchronous "establish connection" call, which will do an async DNS lookup, then attempt to connect to each IP in turn until one succeeds. That would require some other changes, and I'm not sure how it would interact with HTTP keep-alive, for instance. As a lesser solution, would it be reasonable to have a method like Protocols.DNS.prefer_ipv4() to invert the return order of DNS records?
ChrisA