When a zombie kills a villager, the new zombie villager sometimes has equipment.
Maybe it is "Works as Intended", but I think that it doesn't make that much sense.
Steps to reproduce:
1. Set difficulty to hard
2. Summon a zombie
3. Summon a villager
4. Let the zombie kill the villager
5. Repeat steps 1-4 until you notice that the zombie villager has equipment