Comment 2 for bug 1441445

As per the state machine specification, there should not be a transition from CLEANFAIL -> CLEANING directly, and so the REST API is correct. That the internal state machine represents this transition is a bug and should be fixed in Liberty, but there's no need to back port it as this is not exposed in the Kilo API. I have removed that tag, and will close this bug. I have opened a new one here:
  https://bugs.launchpad.net/ironic/+bug/1446758

For reference, I'll quote the spec here as well.
  http://specs.openstack.org/openstack/ironic-specs/specs/kilo/new-ironic-state-machine.html#proposed-change

CLEANING
    Nodes in the CLEANING state are being scrubbed in preparation to being made AVAILABLE. Good candidates for CLEANING tasks include:
    [snip...]
    Management of CLEANING tasks should be handled in the same fashion as ZAPPING tasks.

ZAPFAIL
    Nodes that transition into ZAPFAIL will automatically enter maintenance mode, as failure to ZAP a machine usually indicates a hardware failure or something else that requires remote hands to fix.