Pull request #654 from entrez: the change to avoid impossible
"unpaid_cost: object wasn't on any bill" when examining inventory
while in a wall shared by multiple shops didn't work correctly for
shop-owned objects inside hero-owned containers (which worked prior
to that change).
Not fixed, and possibly not going to be: if a hero-owned container
holds items from more than one shop, the cost appended to those items'
inventory entries might show the wrong amount if the relevant code
picks the wrong shk. Presumably the wrong amount can also happen if
player puts items from one shop into a container owned by another
shop.
Closes#654
c954c267c0