entities (player-created except bow+arrow) will not fire from Minecart

While making sure my gold farm worked in my survival world before 1.9, I found a bug that involved entities not being able to be thrown off a minecart. Further testing showed that no entity can be thrown when on or near a minecart. This still is a problem in 1.9 and above. I tried it with horses and it doesn't seem to work with them as well. I found this out with a snowball and a minecart