I think it's very valuable to have a discussion thread interleaved with patches that get better with more and more feedback (that's what github's pull requests look like to me).

I understand what you mean about the majority of mailing list discussions not starting with a patch though. On github, it would be nice if you could attach a pull request to an existing issue (last time I tried this it didn't work).

Perhaps "pull request" is a bit of a misnomer? Technically speaking it's correct, but if the idea was more that you can interleave patches with a discussion, maybe it wouldn't seem so unpalatable to your way of working. If the discussion doesn't end up merged into "master", just close the issue in question as "wontfix" or similar.