Swimming in the minecart

I got in the mine cart that's on a rail and I was in swimming pose. My view was obscured and in third-person view I was horizontal.

What I expected to happen was...:
I expected to be in sitting pose like normal before snapshot.

What actually happened was...:
I was in swimming pose instead of sitting pose.

Steps to Reproduce:
1. Place mine cart.
2. Right clicked on minecart to get in.
3. Entered and was in swimming pose.