The Stoner issue is a physics bug - the lemming outright does not lose his permanent skills when becoming a Stoner-Ohnoer, unlike the case of a Bomber-Ohnoer.
I know I said I'd have to delay the stable release if there were any new physics bugs, but due to the simplicity of the fix and the pretty much zero breakage potential here (the only situation that would break is if a falling-ohnoer was used to fall into water, combined with a Swimmer, and since you can't do this with a Bomber anymore - which was an intentional change - I think such situations can be filed under "exploiting a bug, so don't care"), I'm going to make an exception for this one and not delay anything.
Fixed in commit a2111c2; Stoner-Ohnoer now behaves the same as Bomber-Ohnoer.