legs go into a block you break minecart while in it

Put the summary of the bug you're having here

What I expected to happen was...:
When i broke a minecart while i was in it i expected
For my character to get out

What actually happened was...:
My legs fell through a block

Steps to Reproduce:
1. get in minecart
2. Break it while in it
3. Your legs fall through block