v0.68
~~~~~

* 'ceph osd crush set <id> <weight> <loc..>' no longer adds the osd to the
  specified location, as that's a job for 'ceph osd crush add'.  It will
  however continue to work just the same as long as the osd already exists
  in the crush map.

* The OSD now enforces that class write methods cannot both mutate an
  object and return data.  The rbd.assign_bid method, the lone
  offender, has been removed.  This breaks compatibility with
  pre-bobtail librbd clients by preventing them from creating new
  images.