Minecraft 1.8.3, Minecraft 1.8.4, Minecraft 1.8.5
Iron Golems attack Zombie Pigmen, triggering Zombie Pigmen to be hostile towards players.
What I expected to happen was...:
Iron Golems used to attack Zombie Pigmen without triggering them to be hostile towards the player, this is what I expect to happen. Iron Golems should not cause Zombie Pigmen to be hostile towards players, either by them not attacking non hostile Pigmen, or by their actions not turning Pigmen against players.
What actually happened was...:
Iron Golems target Zombie Pigmen and trigger the Zombie Pigmen to be hostile towards players. And Iron Golems target specific random Zombie Pigmen, meaning they often won't even defend the player because they are too busy targetting an unreachable Zombie Pigmen.
This means that if there is a single Iron Golem in the Nether, it's impossible to not have Pigmen hostile towards the player, and cause Zombie Pigmen in the normal world to attack the player if there are multiple from gates near a village.
Note: This does not even involve player made Iron Golems, but rather Iron Golems spawned from villages.
Steps to Reproduce:
1. Have a group of Zombie Pigmen and an Iron Golem anywhere near each other.
2. Have a player near Zombie Pigmen.
3. Zombie Pigmen will attack all players forever.