Minecarts in flowing water always go south or east automatically

When a minecart is put on rails in water, flowing out, the minecart will automatically move towards the south or east, depending one the way the rail is aligned.

Steps to Reproduce:

1. Recreate:
   

   [media]

2. Place a minecart on the middle rail

Expected Result:

The minecart would not be biased in its movement to a specific direction.

Observed Behavior:

Depending on the direction you reproduce it in, minecart will always move towards the south or east direction.

Screenshots/Videos: