Pigs do not seem to spawn in Cherry Grove biome

The bug

Pigs do not seem to spawn in Cherry Grove biome. This was mentioned in the biome announcement post:
It’s no wonder that three adorable mobs, pigs, sheep, and bees, are drawn to them and will spawn in this biome.
However, only bees and sheep seem to spawn in the biome.

To reproduce

1. Create a new Cherry Grove single biome world.
2. /tp @e[type=pig] @s
3. No pig will be teleported.