This is a tiny bug, but it might also affect other interactions. If you choose to give Sweynur 3 beers and you have the items in your stash (and not in anyone's personal inventory), then zero beers will be removed, but the quest will still complete:

 

 

Save file: https://www.dropbox.com/s/w6aecw3bx2yceuo/d27d6ae8-7ec6-4f11-9979-253fb2f12ed0%20quicksave.savegame?dl=0

Oh, and about that "free beer" you can get from the barkeeper: