Vines detatchment

What I expected to happen was...:
The vines should break or continue to the ground.

What actually happened was...:
The line of vines stopped at the top of the block. Attached to the bottom of the block and continued to the ground.

Steps to Reproduce:
1. Find a tree with vines.
2. Place a ring around the tree just outside of the leaves.
3. Check the vines touch the ring.

Alternatively You can
1. Place a wall of blocks.
2. Place a line of vines down the blocks.
3. Place block directly on to vines.