As to Bastardization of Implementations; I think from the endless conversation it became obvious (to me at lest) that just what "extension" means is actually somewhat domain-specific, and splitext doesn't really do it's "one thing" very well. 

I think "ignore_leading_dot" is nessecary, regardless of which behavior is default and regardless of if it becomes determined warnings are bad. Dotfiles do exist: on the various *Nix's, and on Mac's too-- I have about a dozen on my primary machine which is a mac in my home directory. Taking them into consideration is important, and there doesn't seem to be a clear opinion on how to treat the dot. So let people decide. IMHO.

I think "all_ext" is quite useful in many situations; that'd be the one I'd actually have used on more then one occasion in the past. I never used splitext because of its lack. And not on UNIX :) My company develops for Windows and OSX.

Either way, I'm curious what the pronouncement will be :) I'll probably update the patch to do whatever is decided is right (assuming that the status-quo of the original modification isn't determined to be right) This doesn't actually affect me at all (due to never using splitext as above noted), I just made the patch because I had time, it was an interesting, and I had an opinion on what was right-- so figured I'd back it up :) It's been more a test-case on getting involved with contributing to python. And an interesting one. :)