librbd:
  copy-on-read:
    Assertion in "rbd_copyup_cb" might fail.
    TODO: maybe there are two callback for the same oid, thus resulting in race
    condition?
librbd:
  In unit test TestMigrate3, make sure destination image has same objects as
  source image.
librbd:
  Migrate the image while opening if possible.
librbd:
  Expose rbd_migrate API, modify unit test to utilize rbd_migrate API, and
  eliminate useless unit tests.
librbd:
  Extend rbd command line tool to create new format image with --newest-format
  option. Also allow rbd command line tool to show information of new format
  image.
librbd:
  Expose C++ binding for migrate.
  Add unit test TestMigratePP.
  Extend rbd command line tool to be capable to migrate RBD image.