Issue reported by ars3niy: with the relatively new container
handling, buying multiple items when some were inside a container
sometimes triggered impossible "unpaid_cost: object wasn't on any
bill" warnings and not buy all intended items. Once that occurred,
subsequent inventory display would repeat the warning.
A couple weeks back, I managed to produce a save file which would
reproduce the problem when 'p' was issued, but failed to figure
out why that was happening. I accidentally deleted that save file
and it took quite a lot of further attempts to get another one.
I still don't understand why this fix is needed, but with it in
place the save file no longer triggers any problems. I'm marking
the issue fixed but that could be premature.
Fixes#1339
ecbb7cff4d