txdb: handle spent coins better.
txdb: handle spent coins better.

VidaID/bcoin,decentraland/bronzeage-node,VidaID/bcoin,VidaID/bcoin,decentraland/bronzeage-node,decentraland/decentraland-node,decentraland/bronzeage-node,decentraland/decentraland-node,decentraland/decentraland-node