Windows 64, version 5.21.b

If a slave drinks a potion from the backpack rather than the chest then the potion takes effect but isn't removed from the backpack.

Can you confirm this? It works correctly for me. 

Yes I just made 3 hair growth elixir, moved them into the backpack. The first two applied ok. The third gave an error invalid get index on 'hairgrowthpot' (on base Dictionary) with error on inventory.gd:382. Repeating this gave the same error on inventory.gd:376. I'd seen the same with amnesia potions before logging this