What I expected to happen was...:
Zombie siege would end

What actually happened was...:
raining flaming zombies from a great height

Steps to Reproduce:
1. Creative mode, generate biomes, structures, cheats on. supposedly my games' seed is 68928445. If I am right, there should be a swamp hut at the origin.
2. Make a new village centered near x=71 y=64 z=-13, carving into rock. Village was founded with a cured zombie. the sandy area is an enclosed horse arena, so only zombies that fell inside the fence dropped meat nearby. (photo)
3. Wait through one zombie siege
4. Note villager movement, might be teleport-ish
5. Next siege, zombies continued to fall from the sky until game got extremely laggy. (photo doesn't do numbers justice) I got a server warning in the launcher.
6. saved my world by logging out, switching back to 13w 16b, logging in and flying to a new chunck. Flew back, all but a few zombies were gone.