Comment 15 for bug 1754174

Also, just confirmed that when running from the live session, PKEXEC_UID is not set (which makes sense, we don't execute under pkexec anymore, in Ubuntu 16.10 and later) and the installer therefore does not drop privileges. So it's altogether reasonable that we don't see any permissions problems in this install path.

The part that doesn't make sense is why 'Install Lubuntu' has permissions errors when 'Install Ubuntu' does not.