What I expected to happen was...:
when i closed the trapped door while i was inside it, the trapped door would clip through me like in all the other versions

What actually happened was...:
i went underneath it and because there was a block under me, i could now walk in a 1 block high tunnel

Steps to Reproduce:
1. place a trapped door above a block
2. stand in the door
3. close the door

because i am not very good ay explaining things i will attach a clip of me executing the bug