Merge pull request #6700 from taosdata/fix/TD-4828

[TD-4828]<fix> handle dnode exit code

src/rpc/src/rpcMain.c

@@ -1189,7 +1189,7 @@ static void rpcProcessIncomingMsg(SRpcConn *pConn, SRpcHead *pHead, SRpcReqConte
       }
       rpcSendReqToServer(pRpc, pContext);
       rpcFreeCont(rpcMsg.pCont);
-    } else if (pHead->code == TSDB_CODE_RPC_NOT_READY || pHead->code == TSDB_CODE_APP_NOT_READY) {
+    } else if (pHead->code == TSDB_CODE_RPC_NOT_READY || pHead->code == TSDB_CODE_APP_NOT_READY || pHead->code == TSDB_CODE_DND_EXITING) {
       pContext->code = pHead->code;
       rpcProcessConnError(pContext, NULL);
       rpcFreeCont(rpcMsg.pCont);