ServerPacketHandler.handleMarkerPoles modifies world off main thread

[Haxy]

 [15:28:31] [Netty Epoll Server IO #9/ERROR] [Sponge]: /* java.lang.Exception: Async Block Change Detected */
> [15:28:31] [Netty Epoll Server IO #9/ERROR] [Sponge]: /* org.spongepowered.common.event.tracking.PhaseTracker.setBlockState(PhaseTracker.java:841) */
> [15:28:31] [Netty Epoll Server IO #9/ERROR] [Sponge]: /* net.minecraft.world.WorldServer.func_180501_a(WorldServer.java:4519) */
> [15:28:31] [Netty Epoll Server IO #9/ERROR] [Sponge]: /* net.minecraft.world.World.func_175656_a(World.java:425) */
> [15:28:31] [Netty Epoll Server IO #9/ERROR] [Sponge]: /* jds.bibliocraft.network.ServerPacketHandler.handleMarkerPoles(ServerPacketHandler.java:1098) */
> [15:28:31] [Netty Epoll Server IO #9/ERROR] [Sponge]: /* jds.bibliocraft.network.ServerPacketHandler.onServerPacket(ServerPacketHandler.java:114) */