only start thread for mine being set to active

src/engine/objects/Mine.java

@@ -575,10 +575,12 @@ public class Mine extends AbstractGameObject {
         if (building != null && !this.isActive)
             building.isDeranking.compareAndSet(true, false);
 
+        if(isAc) {
             Thread zergMechanicThread = new Thread(new ZergMechanicThread(null, this));
             zergMechanicThread.setName(this.zoneName + "Mine");
             zergMechanicThread.start();
         }
+    }
 
     public boolean validForMine(Resource r) {
         if (this.mineType == null)