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:
7033f180 Hoist out synchronisation from ChunkRegionLoader
Spigot Changes:
500ff5d4 Rebuild patches
Additional Paper changes:
Fixed Versioned World Folders to not synchronize on ChunkRegionLoader
Optimized Save Queue even more to use a Long2ObjectOpenHashmap for save map
Add World#getXIfLoaded to IWorldReader to expose it to more places
Also fixes some bugs in ours
Ultimately they both are near the same, but ours is behind the synchronized gate.
Mojangs is mixed behind 2 different synchronization contexts (chunks can lock 2 different objects)
Mojang also blindly unsets the ref on any chunk unload, not just if its the one being pointed to.
Updated Upstream (Bukkit/CraftBukkit/Spigot)
Bukkit Changes:
2dcc44dc SPIGOT-4307: Fix hacky API for banners on shields
e0fc6572 SPIGOT-4309: Add "forced" display of particles
efeeab2f Add index to README.md for easier navigation
f502bc6f Update to Minecraft 1.13.1
CraftBukkit Changes:
d0bb0a1d Fix some tests randomly failing
997d378d Fix client stall in specific teleportation scenarios
b3dc2366 SPIGOT-4307: Fix hacky API for banners on shields
2a271162 SPIGOT-4301: Fix more invalid enchants
5d0d83bb SPIGOT-4309: Add "forced" display of particles
a6772578 Add additional tests for CraftBlockData
ce1af0c3 Update to Minecraft 1.13.1
Spigot Changes:
2440e189 Rebuild patches
4ecffced Update to Minecraft 1.13.1