MinecraftForge/MinecraftForge — pull request #270 by ScottKillen (2012-11-21 04:46:18+00:00)
Title: Slime spawn rules override

Slime entities have hardcoded rules to control spawning. Vanilla slimes can only spawn underground in certain chunks or in Swamp biomes at night at certain y-axis values, regardless of the wider-scope spawn settings.

This change uses a LivingSpecialSpawnEvent to allow mods to override slime spawning rules.