[BUG] org.eclipse.jetty.io.nio.SelectorManager too busy

Happened upon JVM shutdown, saw it accidentally in the log:

```
[13/Jul/2021:23:26:33,150] WARN  nio: Selector org.eclipse.jetty.io.nio.SelectorManager$SelectSet@41137f66 keys=1 selected=0 is too busy, pausing!
```

Jetty is used in bt-upnp module.