podman unshare prints Failed to connect to system scope bus via local transport: Operation not permitted (consider using --machine=<user>@.host --user to connect to bus of other user)

[eriksjolund]

On a Fedora CoreOS 43.20250929.1.0 (with Podman 5.6.1)

1. Log in as root
2. useradd test
3. machinectl shell --uid=test
4. podman unshare
   The following output is printed

   Failed to connect to system scope bus via local transport: Operation not permitted (consider using --machine=<user>@.host --user to connect to bus of other user)
   

Here is the same text with some newlines added

Failed to connect to system scope bus via local transport:
Operation not permitted (consider using --machine=<user>@.host --user
to connect to bus of other user)

Is the output expected?

(I don't remember seeing this before. Maybe it started a few months ago)

click me for details

root@localhost:~# useradd test
root@localhost:~# machinectl shell --uid=test
Connected to the local host. Press ^] three times within 1s to exit session.
test@localhost:~$ podman unshare
Failed to connect to system scope bus via local transport: Operation not permitted (consider using --machine=<user>@.host --user to connect to bus of other user)
root@localhost:~#