Re-fixed block transmutation

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

@@ -372,6 +372,7 @@ public class Chunk {
                 flag = j >= k1;
             }
 
+            if (chunksection.a(i, j & 15, k) != l) return false; // CraftBukkit - remove next update
             chunksection.a(i, j & 15, k, l);
             int i2 = this.x * 16 + i;
             int j2 = this.z * 16 + k;