Comment 4 for bug 1931588

Also, in the action this innocuous looking line [0]:

 diff_nodes = update_node_list()

Actually runs the set maintenance and delete commands [1].

I suspect the bug is at or near [1]. It is possible the maintenance setting has not completed yet before we attempt the delete.

[0] https://github.com/openstack/charm-hacluster/blob/master/actions/actions.py#L123
[1] https://github.com/openstack/charm-hacluster/blob/master/hooks/utils.py#L1566-L1567