Update converter.py

Author: noranhe

vnpy/trader/converter.py

@@ -341,7 +341,7 @@ def convert_order_request_net(self, req: OrderRequest) -> List[OrderRequest]:
                 yd_req.volume = yd_volume
                 reqs.append(yd_req)
 
-            if volume_left:
+            if volume_left > 0:
                 open_volume = volume_left
 
                 open_req = copy(req)
@@ -364,7 +364,7 @@ def convert_order_request_net(self, req: OrderRequest) -> List[OrderRequest]:
                 close_req.volume = close_volume
                 reqs.append(close_req)
 
-            if volume_left:
+            if volume_left > 0:
                 open_volume = volume_left
 
                 open_req = copy(req)