Steps to reproduce:

1. Connect two devices
2. flutter run -d all on some Flutter app (e.g. flutter create template app)
3. Turn the screen off on one of the devices.
4. Press "P" to show the performance overlay.
5. Press "h" to show the help.

Expected results: Performance overlay shows on the device whose screen is on. Help screen displays in the console.

Actual results: Nothing happens (assuming the phone you turned off happens to be the one we try to update first). User gets very confused and things everything has hung.