Glazed Terracotta Blocks are still sometimes moved by pistons

Release_466466

Summary:
From MCM-81. Pistons will now push these blocks but not pull them. They should neither push nor pull glazed terracotta.

Impact:
Contraptions decorated with Glazed Terracotta Blocks break. BLOZARK features a couple of these contraptions, and they would need to be changed to either obsidian or bedrock to fix, which would break the visual of the room.

Repro Steps:
1. Create a new world
2. Give yourself a sticky piston, any color of Glazed Terracotta Block, and a Redstone Block
3. Place the sticky piston pointing up, and place the Glazed Terracotta Block on top of it.
4. Place the Redstone Block next to the piston to power it
5. You will notice the Glazed Terracotta Block has moved up. Unpower the piston. You will notice the block has stayed in place.

Observed results:
Piston extends, moves the block, and leaves the block there.

Expected results:
Piston should not extend.

Screenshots/videos attached:
No