While bda's usecase is indeed fixed is recent versions, I want to point out the issue still exists in a recent py3k checkout. I've updated my patch to apply cleanly against recent py3k (and made less structural changes to test_socketserver.py; I still think it has an archaic unittest structure but I want this patch to remain relevant a bit longer, maybe fix the structure at a later time).

Again, I argue that resolving the general case (a generic untilConcludes to be exposed in stdlib) is hard and that we have a patch review worthy (IMO) solution at hand. Let's apply it (and possibly open a separate ticket for the generic case, if that's deemed interesting).