MCM-166[BLOCKING] Minecarts seem broken
Verification builds
WIN10 1.2.11_r-0h3 (686814)
Summary
Minecarts have stopped moving / animating movement (not exactly sure which one).
When entering a minecart either on powered rails or normal rails, it seems to be stuck in place.
Sometimes it jumps around the rail with no discernible pattern
Impact
Minecarts are unusable altogether
Steps to Reproduce
1. Create new world
2. place a minecart on rails (powered or regular does not seem to matter)
3. Enter the minecart
4. press `forward` in any available direction
Expected Result
Minecart should ride along the rails, animating correctly
