Double grass spawns peony block when broken

Put the summary of the bug you're having here

I attacked the bottom block of a double grass, expecting both blocks to break.
After destroying the bottom block, a peony blockspawnes in the place of the top grass block, then shortly disappeared.

Steps to Reproduce:
1. Locate double grass
2. Destroy the bottom grasss block (you may need to be walking or sprinting)
3. Watch the top block carefully