Comment 1 for bug 1735719

This is because the compute node for that host in that cell is not deleted and since it was mapped once, it is marked as 'mapped' again, so the discover_hosts routine ignores it, for performance / efficiency reasons.

This likely means that the delete_host CLI is not checking to see that the actual compute node is gone from the cell before deleting the host mapping, or if it will delete the host mapping, it should mark the compute node as mapped=0 so it can be discovered again.