Formatting step reliably failed during installation attempts at ZurichZHF

[mfrischknecht]

During my installation attempts today, the formatting step of the installer reliably failed (I'm using LUKS, but I'm not sure if that's an important factor). I don't have the error present anymore, but the issue popped up in installer runs without --debug when I selected "yes" at the formatting step.

The current suspicion is that disko doesn't like being invoked "without" stdout.