This is mostly fixed with the new build 1.06 on EXP servers, when you empty a Jerry Can/Cook Pot of liquid it changes your stamina correctly (no longer reduces your stamina the full amount even if container is empty). The only issue I saw is that the weight value displayed on the client when you inspect the item doesn't change until you re-log, after re-log it shows the correct value depending on how much liquid is in the container.

The weight is still displayed wrong on the client when you empty gas can or cooking pot, until you logout then it shows up correct. Also when your clothes get wet and you wring them out to dry, the weight does not update correct until you move an item into or out of the clothes.