Druids can break bedrock

[Newellis]

Describe the bug when druids regenerate a mine they can replace bedrock with stone.

To Reproduce Steps to reproduce the behavior:

1. create a mine with bedrock in/as the floor(I used a bedrock superflat world)
2. have a miner dig out the mine for a bit
3. wait for a druid to come along and regenerate the mine
4. watch druid replace the bedrock with stone or ore

Expected behavior bedrock should be unchanged by the druid