Wine Merchant and Villa handled incorrectly

[JW]

I bought Villa with at least 2 coins unspent. I was able discard my Wine Merchants from my tavern mat because I was returning to the action phase. Game #206177 on oregon.

Donald tentatively ruled that buying Villa should not let a player discard Wine Merchant: http://forum.dominionstrategy.com/index.php?topic=16815.msg668680#msg668680

I buy Villa with at least 2 coins unspent. Can I discard my Wine Merchants from my tavern mat because I am returning to the action phase?

I am going to tentatively rule that no, you didn't reach the end of your Buy phase. I feel like that's the most intuitive answer.