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
CraftBukkit Changes:
eb2e6578 SPIGOT-5116: Fix concurrent modification exception inside ChunkMapDistance
989f9b3d SPIGOT-4849: Fix server crash when accessing chunks during chunk load/unload/populate events
f554183c SPIGOT-5171: Don't fire PlayerTeleportEvent if not actually moving
2349feb8 SPIGOT-5163: Cancelling PlayerBucketFillEvent visually removes the targeted block
Spigot Changes:
9a643a6a Remove DataWatcher Locking
An oversight in this patch may be to blame for several issues in certain
cases, we'll opt to using a queue as this will fall in line with what is
expected and may help some issues where chunks remain loaded or fail to
load
Shane Freeder