Thank you, it works!

"based on the information given within this ticket how would I know that". Actually, the issue is "different physics applied to exp orbs on slime blocks", Snocrash farm is an exemple, so you may know entity-activation-range.misc is the cause… But I recognize it is hard to think about that without reproducing the bug.

I take that back, there is a reproducible difference after you use the snowballs to provoke the pig zombies (based on the information given within this ticket how would I know that).
This is because Spigot has configuration for various things.

In this case setting entity-activation-range.misc to 0 to disable configurable activation of experience orbs (along with merging, although didn't test if that is required) the behaviour is the same.

Once again I cannot discern any difference when joining this map on single player, craftbukkit or spigot.

If you want this issue you need to provide detailed steps to reproduce (I simply joined the map and stood on the wool near the chest gathering exp). You should also build a minimal contraption that isn't hundreds of blocks big relying on potentially hundreds of different behaviours and takes minutes to test each time.

Same issue in 1.11.2, I have made some tests, during 5 minutes :

Vanilla server : https://image.noelshack.com/fichiers/2017/07/1487081297-2017-02-14-14-10-43.png

Spigot with default exp orbs merging : https://image.noelshack.com/fichiers/2017/07/1487081298-2017-02-14-14-35-35.png

Spigot with 0.0 exp orbs merging : https://image.noelshack.com/fichiers/2017/07/1487081298-2017-02-14-14-47-36.png

CraftBukkit : https://image.noelshack.com/fichiers/2017/07/1487081297-2017-02-14-14-59-51.png

The server was running on my computer (Windows 8.1 with MinGW, Java 1.8.0_111-b14). I made a new instance of Minecraft, no mods. No plugins on server, view-distance 12, difficulty hard (as recomanded by Snocrash in his tutorial).

Please reopen this bug.

Works fine here, both with and without exp merging enabled.

Done that, doesn't fix it ^^

Try to edit your spigot.yml and set "merge-radius", "exp" to 0

Only happens on spigot, not on craftbukkit