v0.75
~~~~~

- 'rbd ls' on a pool which never held rbd images now exits with code
  0. It outputs nothing in plain format, or an empty list in
  non-plain format. This is consistent with the behavior for a pool
  which used to hold images, but contains none. Scripts relying on
  this behavior should be updated.

- The MDS requires a new OSD operation TMAP2OMAP, added in this release.  When
  upgrading, be sure to upgrade and restart the ceph-osd daemons before the
  ceph-mds daemon.  The MDS will refuse to start if any up OSDs do not support
  the new feature.