maxscale 2.5.3 connection has been idle

[ccll ddd]

I use maxscale 2.5.3 to readwrite splite. but found an error:

```

Lost connection to the master server, closing session. Lost connection to master server while connection was idle. Connection has been idle for 132 seconds. Error caused by: #HY000:  (110, Connection timed out)erver: network error. Last close reason: <none>. Last error:

```

I read the code :

```

if (!can_continue)
        {

            int idle = duration_cast<seconds>(
                maxbase::Clock::now(maxbase::NowType::EPollTick) - backend->last_write()).count();
            MXS_ERROR("Lost connection to the master server, closing session.%s "
                      "Connection has been idle for %d seconds. Error caused by: %s. "
                      "Last close reason: %s. Last error: %s", errmsg.c_str(), idle,
                      mxs::extract_error(errmsgbuf).c_str(),
                      backend->close_reason().empty() ? "<none>" : backend->close_reason().c_str(),
                      reply.error().message().c_str());
        }

        // Decrement the expected response count only if we know we can continue the sesssion.
        // This keeps the internal logic sound even if another query is routed before the session
        // is closed.
        if (can_continue && expected_response)
        {
            m_expected_responses--;
        }

        backend->close(failure_type);
        backend->set_close_reason("Master connection failed: " + mxs::extract_error(errmsgbuf));

```

it should log "Master connection failed: ",

but I don't found this error log.