Issue still exists in 1.13 pre 8. Closing Half slab windows will change the pathing of Baby ZPs back to the destruction spot.
Sorry. For the vagueness of description. I find the search in the MC JIRA a little bit confusing and was not sure if I had new unreported issue.
The issue is reproduced by loading the world file of Zombie Pigmen Farm design available at https://www.mediafire.com/file/by2w8r7dp8qtua6/Nether+gold_xp+farm+ilmango.zip
In 1.12 the Baby ZPFs will properly track to the player and end up in the destruction trap. In 1.13 their tracking has changed and they stackup on the the path that is not direct but one block off.
Workaround for the build is to add some half slabs at the 8 points where they are tracking which then allows them to track over to the trap.
Still exists in 1.10
MC-94554 appears to be resolved by this update. Use of example world 1.9Fix-Ultimate-XP-Gold-Farm-bySnocrash no longer causing server to crash with the snapshot 16w14a.
The Zombies do move slowly while trying to track on you. When they figure out their paths you experience a strange speed up effect as they charge you. Then next batch spawns in and the process repeats. FPS remained at near 60 entire test.
Not sure how that relates to MC-94438.
I was actually voting for and following MC-94554 but it was combined in this bug report.
I can confirm. If anyone thought these releases fixed issue. It did not. I am getting sick of all zombie mobs causing lag on even SMP servers. I have only 7 to 10 users and any mob relying on new tracking is throwing up errors. Please fix. I rather have stupid mobs than having server crash constantly trying to keep up with complicated player / mob tracking. Having Smart mobs is Totally not worth it.
Issue still present in 1.13