[PVE-User] ceph disk replace

[mj]

For the archives:

The issue was caused by the hammer -> jewel upgrade setting:

> setuser match path = /var/lib/ceph/$type/$cluster-$id

which we forgot to remove from ceph.conf after the jewel upgrade and 
completing the chown-ing of OSD data.

After we removed the line from ceph.conf, no restart or anything, we 
could add the OSD/journal as expected.

Hope this helps someone else in the future :-)

MJ