Parrot summoned with negative Age has smaller hitbox

The bug

A parrot summoned with a negative Age has a smaller hitbox, as if it was a baby.
Since MC-148210 has been fixed, this report should be valid as well.

How to reproduce

1. Enable hitboxes being shown: F3+B

2. Summon a parrot with a negative Age

   /summon parrot ~ ~ ~ {Age:-12000,NoAI:1b}

   /summon parrot ~ ~ ~ {Age:-12000,NoAI:1b}