Fix issue #909: static queue in Loop

Author: facontidavide

include/behaviortree_cpp/decorators/loop_node.h

@@ -60,7 +60,8 @@ class LoopNode : public DecoratorNode
       // special case: the port contains a string that was converted to SharedQueue<T>
       if(static_queue_)
       {
-        current_queue_ = static_queue_;
+        current_queue_ = std::make_shared<std::deque<T>>();
+        *current_queue_ = *static_queue_;
       }
     }