Can't breed spawner mobs

You can't use wheat to breed cows from spawners. The nametag disappears, but it doesn't breed the mobs. Not sure if this is actually a bug or intended. The one case I can think of where someone may want to do this would be if they wanted to buy a spawner to start a farm in their base, but don't want to deal with the risk of having the spawner raided. (if this is changed, also consider if the bred mobs should have AI, if I remember correctly mobs spawned from breeding chickens from eggs and likely natural passive mobs are "vanilla" (have AI, do not stack) but spawner mobs don't have AI).