Problem
Setting Auto_Pickup=/ will still pickup rocks, even though the 'o' setting exists to separate rocks from other missiles and decide whether to pick them up or not.

How to reproduce it
Drop a bundle of arrows and a heap of rocks in the same tile. Set Auto_Pickup=/ (using the ':=' command) and walk over that tile. You will pick both items up. Drop them again, set Auto_Pickup=o and walk over that tile again. Only rocks will be picked up now.

Notes
N/A