Comment 9 for bug 1770962

If I delete the serial device from my VM (with either ovmf or seabios), the 'serial' command returns an error. So that also seems useful. OTOH, the error message refers to com0, so maybe it's not all /that/ smart about what device it's talking to.

If I configure *two* serial ports in a VM, grub output appears only on the first.

Regardless, I think it's reasonable for the installer image in particular to output to both serial and graphical out of the box, even if it's doing so blindly.