Description of problem:
Fence agent scripts check whether the host went down when doing reboot, so we can remove the logic we do in the engine, and replace it with calling the reboot option of the fence agents.

More details in
https://github.com/ClusterLabs/fence-agents/blob/master/fence/agents/lib/fencing.py.py

important lines starts at 820 where code switch for cycle / non-cycle. Non-cycle is what interested you, this code is covered at 832-851.