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:
e601e7aa SPIGOT-5540: Adding items to inventory causes legacy-data loading
CraftBukkit Changes:
596b0b2d SPIGOT-5514: VehicleEntityCollisionEvent triggered by passengers
78dfb77e71