Iron golems no longer actively seek out hostile mobs

The bug

Iron golems no longer aggressively seek out dangerous mobs near its village unless attacked. It does work to an extent still however. Any time between immediately and after a long pause, the iron golem will attack the mob(s), but by that time it can be too late for a villager.

How to reproduce

You simply need a village capable of spawning an iron golem. After nightfall you can notice it seems "unaware" of many of the hostile mobs until they have been nearby for a short time.

Code analysis

Code analysis by Marcono1234 can be found in this comment.