Minecarts activate tripwire directly above them. "Snapshot" 14w08a

When a minecart goes under a tripwire trap one block above the ground (as shown in the picture), it is activated. This didn't happen in the previous version (1.7.4), and the only way a redstone output could be achieved was having an entity ride the minecart. I assume that this is a bug, since it hasn't been mentioned that minecart'd dimensions have changed.