mv of a data root onto a non-empty directory fails (Directory not empty).
The romm/copyparty cutover creates Containers/<svc>/ before migrating:
the seed env file lands there first, and the romm anonymous-volume rescue
extracts into it before the /opt move. Merge the old root's entries in
without overwriting existing state (mv -n), warn and leave residue if a
collision kept the new side, and keep the plain rename when the
destination is absent or empty.
Frank
cdfaf48191