If the user (erroneously) runs as root while modifying their user
installation, e.g. with "sudo flatpak --user install ...", this can
cause "permission denied" errors later on when they try to operate on
the installation as their own user. So refuse to execute a transaction
on a user-owned installation as root. Root can still operate on their
own per-user installation.
This approach does have a weakness: if flatpak is running as root when the user
installation is first created, it will be owned by root and therefore
avoid this check. I'm not sure what could be done about that.
Fixes https://github.com/flatpak/flatpak/issues/2565Closes: #2575
Approved by: alexlarsson