Superflat using Biome 128 generates as "Ocean" instead of "Plains M"

Generate a superflat world using biome ID 128, something like: 3;minecraft:bedrock,2*minecraft:dirt,minecraft:grass;128;village

Load the world and press F3, it shows a biome of "Ocean" instead of "Plains M".

Is this a bug? Or is the wiki wrong about the biome IDs?