The driver do a sanity check that the to-be-cloned volume is not available. But the tm/delete action is not called by OpenNebula when a VM is in "UNDEPLOYED" state.
Workaround: Re-run the delete-recreate request. It will pass becacuse the VM is in PROLOG_FAILURE and OpenNebula will call the tm/delete script to do the cleanup before calling tm/clone.