when openstack is configured to auto assign floating IP addresses from pool to created instances,
for example like: http://www.sebastien-han.fr/blog/2012/08/03/openstack-auto-assign-floating-ip/
deleting host from foreman fails with exception and host cannot be deleted.

more info about it can be found at:
https://bugs.launchpad.net/nova/+bug/1150772
https://review.openstack.org/#/c/24119/

i think we can ignore those errors, so host can be deleted on environments with this configuration.