I happened to see this bug listed (http://forum.shuffleit.nl/index.php?topic=1226.msg3671#post_Merchant). This is actually correct behavior, not a bug. Donald has confirmed this in this thread (where Ingix also participated): http://forum.dominionstrategy.com/index.php?topic=20153.msg826012#msg826012
Thanks for pointing it out and reminding me. I removed the bug from the list.