Fixed fatal crash at world generation.

src/main/java/net/minecraft/server/WorldGenerator.java

@@ -29,7 +29,7 @@ public abstract class WorldGenerator {
     protected void setTypeAndData(BlockChangeDelegate world, int i, int j, int k, int l, int i1) {
         if (this.a) {
             world.setTypeIdAndData(i, j, k, l, i1);
-        } else if (world instanceof World && ((World)world).getChunkAtWorldCoords(i >> 4, k >> 4).seenByPlayer) {
+        } else if (world instanceof World && ((World)world).getChunkAtWorldCoords(i, k).seenByPlayer) { // CraftBukkit - remove in next update
             if (world.setRawTypeIdAndData(i, j, k, l, i1)) {
                 ((World)world).notify(i, j, k);
             }