On mån, 2011-04-25 at 15:26 -0400, Tom Lane wrote:
> Well, it's not just to be "helpful", it's to close off code paths that
> are never going to be sufficiently well-tested to not have bizarre
> failure modes. That helps both developers (who don't have to worry
> about testing/fixing such code paths) and users (who won't have to
> deal with the bizarre failure modes).
That's of course another good reason.