newly spawned pigman not agro while other pigmen are, and any pigman that did not see the attack will not become angry. This breaks current gold/xp farms with pigmen.

What I expected to happen was...: 

When current pigmen are agro towards the player and new pigman come in range of the agro pigman, they should become agro towards the player

What actually happened was...:
The newly spawned pigmen, and other pigmen, are not agro towards the player

Steps to reproduce:
1. Go to Nether

2. hit a pigman

3. do not kill all agro pigmen

4. run to newly spawned pigmen, or pigmen that did not see the attack

5. these pigmen will not become agro towards player, even when they see the other agro pigman