Mojang was not checking that the chunk did not overwrite, or
was successfully removed.
We're seeing odd reports in #1561 that indicates issues around
this are having problems.
Upstream has released updates that appears to apply and compile correctly.
This update has not been tested by PaperMC and as with ANY update, please do your own testing
Bukkit Changes:
39ce5d3a SPIGOT-4399: ItemMeta.equals broken with AttributeModifiers
CraftBukkit Changes:
1cf8b5dc SPIGOT-4400: Populators running on existing chunks
116cb9a1 SPIGOT-4399: Add attribute modifier equality test
5ee1c18a SPIGOT-4398: Set ASM7_EXPERIMENTAL flag
