Fix placement of scheduler tick

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

@@ -425,6 +425,8 @@ public class MinecraftServer implements Runnable, ICommandListener {
         Vec3D.a();
         ++this.ticks;
 
+        ((CraftScheduler) this.server.getScheduler()).mainThreadHeartbeat(this.ticks);
+
         for (j = 0; j < this.worlds.size(); ++j) { // CraftBukkit
             // if (j == 0 || this.propertyManager.getBoolean("allow-nether", true)) { // CraftBukkit
                 WorldServer worldserver = this.worlds.get(j); // CraftBukkit
@@ -437,7 +439,6 @@ public class MinecraftServer implements Runnable, ICommandListener {
                     }
                 }
 
-                ((CraftScheduler) this.server.getScheduler()).mainThreadHeartbeat(this.ticks);
                 // CraftBukkit end
 
                 worldserver.doTick();