That's because it's pre-IDN (and it fails for IP address literals as well). This actually strengthens one of the points I was trying to make: the need to fail

That's because it's pre-IDN (and it fails for IP address literals as well). This actually strengthens one of the points I was trying to make: the need to fail gracefully. The application I took the snippet from (which has been retired some years ago) would have accepted IDNs after asking the user for confirmation.