what is the gain in splitting the conversation about a project between mailing list and github pull requests? Indeed pull requests are often cathedral in the desert, often without a single comment. To centralize the discussion in the mailing list makes a lot more sense IMHO, and exposes it to a much wider audience.
Good point, I don't think conversations should ever be split if possible as this is confusing. I contribute to quite a few projects that only have a github project and associated issue tracker though, and "pull requests as conversations" seem to work fine in those cases.
These projects are generally smaller than redis though :-)
