When a chest is in the ground immediately in front of a two block tall doorway, it does the same thing as soul sand. Since it isn't a whole block tall, you can't walk through the doorway without jumping.

What I expected to happen was...:
Walk through the doorway unimpeded.

What actually happened was...:
I stopped and had to jump.

Steps to Reproduce:
1. Create a doorway with a chest. C=Chest, X=Normal Block, .=Air. First Layer (vertical):
XXX
X .X
X .X
XXX
Second layer:
X .X
X .X
X .X
XCX
2. Attempt to walk through the doorway, from the side with the chest.
3. You get stuck, as with soul sand.