Vendors Kegs which are containers are not seen as containers by vendors

[BrianFreud]

When you put an old Keg which is a container onto a vendor, the vendor will not see it as a container, and will not allow it to be set not-for-sale.

 

[BrianFreud]

Clarification: these are the kegs with closed top, like a potion keg, not the open top ones.