Reproducible using r20463 server.
When throwing a spell-potion (e.g. potion of Rainbow Wave) that is cursed, the spell the potion is supposed to cast is still cast. Given how other cursed items work, it feels like this should do something other than work properly.
I had a thought that the cursed potion compels you to drink it instead of throw it, but I hadn't investigated the effects of drinking those potions yet, so it may be too much/little punishment. I'd like some input as to whether this would be a good way to handle it or not.