Stack_health validation is failing due to invalid token if fresh inventory file is not being before validation being run. Include a step to generate static inventory during post-upgrade to avoid this failure.
It appears that the inventory is actually regenerated during the upgrade process and stored in the $HOME/config-download dir.
*** Bug 2118673 has been marked as a duplicate of this bug. ***
Hey, heat-admin is the default in 16.x (train): https://github.com/openstack/python-tripleoclient/blob/stable/train/tripleoclient/v1/overcloud_deploy.py#L803
Updated doc at 16.2: https://access.redhat.com/documentation/en-us/red_hat_openstack_platform/16.2/html-single/framework_for_upgrades_13_to_16.2/index