Horses spawn in blocks during world generation, causing them to suffocate

The bug

When I created a minecraft world, I was next to some horses. Two of the horses suffocated to death since they spawned inside blocks. Also, the horse animation was a little bit off.

How to reproduce

1. Seed: 2154973
   World Type: Default
   Coordinates: /tp -129797 70 -3328 0 90

Code analysis

Based on 1.11.2 decompiled using MCP 9.35 rc1

The problem seems to be that the method net.minecraft.world.WorldEntitySpawner.performWorldGenSpawning(World, Biome, int, int, int, int, Random), which is called when a chunk is populated, does not test if the entity it wants to spawn is colliding before spawning it in.