TNT minecarts sometimes detonate when going around corners

The Bug:

TNT minecarts sometimes detonate when going around corners.

Steps to Reproduce:

1. Build the setup shown in the attachment below. setup.png
2. Place a TNT minecart on the rail next to the diamond block.
3. Push the TNT minecart along the rails.
4. Take note as to whether or not TNT minecarts sometimes detonate when going around corners.

Observed Behavior:

TNT minecarts sometimes detonate when going around corners.

Expected Behavior:

TNT minecarts would not detonate when going around corners.