Too many Librarian villagers and no farmers

I know villager spawning has gotten messed up before, and it's messed up again. Instead of farmer villagers spawning, about twice as many librarian villagers have spawned than should have. None of the villagers are tending crops. The spawning was fine in snapshot 15w34c but is not in 15w34d, so I assume this happened with the 15w34d update.