Baby zombies spawned by right-clicking onto an adult zombie never spawn with any weapon/armor and never rarely spawns as a chicken jockey

The bug

Relates to MC-165960.

Right-clicking onto an adult zombie will always spawn unarmed/unarmored baby zombie regardless of type of zombie it is.

How to reproduce

1. Set difficulty to hard
2. Spawn a zombie
3. Hold out the zombie spawn egg and right-click onto the zombie
   → All of the baby zombies do not randomly spawn with armor, iron swords, iron shovels or even spawn as a chicken jockey (Tridents/fishing rods/natilus shells for baby drowned)

See images below.