When a mine cart is pushed through a nether portal, it always lands in an air block if possible rather than on track.

Setup: A nether portal is built in the nether and in the exact corresponding position and direction in the overworld. A mine cart track runs "through" the portal in both dimensions.

Issue: When a mine cart is pushed through the portal, it never lands on the track. When the track is on the left side of the portal, the mine cart lands on the right side. When the track is on the right side of the portal, the mine cart lands on the left. This happens in both north/south and east/west portals. Placing a solid block to block off the side opposite the rails appears to cause the mine cart to land in the exact center of the portal. In other words, a rail is treated as an obstruction rather than a valid place to put a mine cart that has just passed through the portal.