The default controls:
Assigned to the second control slots, unless there was no default (2 player) so it's assigned to the first control slots.
I declined to do this for .21 because I was concerned with how the control menu worked when both control slots were filled. Turns out I had nothing to worry about: predictably you'll only change the first slot unless you clear the setting with Backspace. So the joy settings are safe.
I would have liked to also fill only the second control slots for 2 player, but the menu acts a little weird when the second slot is filled but not the first. So I'll let it slide.
+1 means this gets merged in.