Issue Description:

Bedrock ceiling in Nether is broken, contain netherrack block. Only BoP mod installed, nothing else.

Steps to reproduce:

1. Create BoP world with seed 4565
2. Go to nether coordinates -15,128,-113
3. See netherrack block around

Additional Information:

• Screenshots:
  

Affected Versions (Exact numbers, do NOT use "latest"):

• Biomes O' Plenty: BiomesOPlenty-1.12.2-7.0.1.2399-universal
• Minecraft: 1.12.2
• Forge: 14.23.4.2765
• Java: 1.8.0_181

Never closed this, but I'm pretty sure this was fixed months before this issue was even opened.

Wasn't this semi intended by the mod originally? I think it has been in place for a while I dont recall why tho...

In the past versions I've seen small lakes on top with quick sand or blood, which allowed to break thru. In versions before latest one, it was no longer the case. This new thing actually does not allow you to break thru bedrock, because under top layer there are still 4 more layers of bedrock and I could not get thru. But it does allow mobs to spawn above bedrock, which is a game change, if you are building a mob farm at higher levels. Anyway, developers who actually made this change should tell us if this is intended change or a glitch.

Mobs spawning on top is a Minecraft change, not a mod. That is not Biomes O Plenty. So you will have to ask Mojang.

Unless I missed some recent changes from Mojang, mob spawning on top of bedrock was not allowed, but when there are few netherrack blocks instead, it is allowed.