Currently "branch support" is a property of DiffusionRequest, which is mostly a URI-parsing/routing class that handles bundling up and unbundling all the commit/path/line/branch information in a source/xyz/master/path/to/thing.c;abcd1234$12 URI.

This is a legacy sort of thing; I moved it to Repository instead.

I pulled this piece of logic ("find all the URIs which point to this install [with an HTTP/HTTPS protocol]") up into a parent class.