When I grow a propagule, the mangrove tree can break the bedrock layer of the nether.

What I expected to happen was...:
That the mangrove tree didn't grow under the bedrock layer of the nether.

What actually happened was...:
The mangrove tree can break the bedrock if it's at the right height.

Steps to Reproduce:
1. Go to the nether;

2. Place a propagule at 4-6 blocks under the bedrock layer.

3. Make it grow.