Unable to throw snowballs at target while sitting in a minecart

previously (1.8.x) sitting in a moving minecart, one can throw snowballs in addition to using a bow and arrow, to hit a target without damaging it significantly (such as nametagged pigmen in a gold farm) in order to aggro the rest

I am not certain how long the bug has existed in the snapshots but I noticed it several versions back from the version herein reported.

bow and arrow still work as expected, but one cannot even throw a snowball straight upwards from within a minecart.

after some additional testing, i discovered I could occasionally make it work, but not repeatably.