Not spawn baby mobs when right clicking spawn egg or summon mobs with "IsBaby" tag in there

I tried to spawn baby mobs using spawn egg:
/give @p spawn_egg 1 0 {EntityTag:{id:"Villager",IsBaby:1b}}
and /summon Pig ~ ~ ~

{IsBaby:1b}

It spawn normal villager instead of baby villager, like minecraft has removed baby mobs from the game.
Question:
1. Why baby zombie villager head is more bigger O_o?? like in MCPE.
Mobs:
1. Chicken
2. Pig
3. Cow
4. Villagers
5. Rabbits
6. Mushroom Cow
7. Horses Tamed/Untamed
8. Sheep
9. Wolf Tamed/Untamed
10. Ozelot Tamed/Untamed
This bug same as baby topic from MC-88172