Update task fails on RHOS 16

[greg-hellings]

Trying to run update on RHOS 16 fails with the following error:

TASK [run overcloud-update script] ***********************************************************************************
Wednesday 20 January 2021  14:47:29 -0600 (0:00:00.041)       0:08:24.395 ***** 
fatal: [10.0.162.83]: FAILED! => changed=true 
  cmd: |-
    source ~/stackrc ;
    ~/overcloud_update.sh
  delta: '0:00:02.611775'
  end: '2021-01-20 15:43:36.170945'
  msg: non-zero return code
  rc: 2
  start: '2021-01-20 15:43:33.559170'
  stderr: ''
  stderr_lines: <omitted>
  stdout: |-
    openstack: 'overcloud update stack -i overcloud' is not an openstack command. See 'openstack --help'.
    Did you mean one of these?
      overcloud admin authorize
      overcloud cell export
      overcloud config download
      overcloud container image build
      overcloud container image prepare
      overcloud container image tag discover
      overcloud container image upload
      overcloud credentials
      overcloud delete
      overcloud deploy
      overcloud execute
      overcloud export
      overcloud external-update run
      overcloud external-upgrade run
      overcloud failures
      overcloud generate fencing
      overcloud image build
      overcloud image upload
      overcloud netenv validate
      overcloud node bios configure
      overcloud node bios reset
      overcloud node clean
      overcloud node configure
      overcloud node delete
      overcloud node discover
      overcloud node import
      overcloud node introspect
      overcloud node provide
      overcloud node provision
      overcloud node unprovision
      overcloud parameters set
      overcloud plan create
      overcloud plan delete
      overcloud plan deploy
      overcloud plan export
      overcloud plan list
      overcloud profiles list
      overcloud profiles match
      overcloud raid create
      overcloud role list
      overcloud role show
      overcloud roles generate
      overcloud roles list
      overcloud roles show
      overcloud status
      overcloud support report collect
      overcloud update converge
      overcloud update prepare
      overcloud update run
      overcloud upgrade converge
      overcloud upgrade prepare
      overcloud upgrade run
      undercloud backup
      undercloud install
      undercloud minion install
      undercloud minion upgrade
      undercloud upgrade
  stdout_lines: <omitted>
...ignoring

TASK [print overcloud failures] **************************************************************************************
Wednesday 20 January 2021  14:47:33 -0600 (0:00:03.547)       0:08:27.943 ***** 
fatal: [10.0.162.83]: FAILED! => changed=true 
  cmd: |-
    source ~/stackrc ;
    openstack stack failures list --long overcloud
  delta: '0:00:02.565234'
  end: '2021-01-20 15:43:39.939227'
  msg: non-zero return code
  rc: 1
  start: '2021-01-20 15:43:37.373993'
  stderr: 'ERROR: The Stack (overcloud) could not be found.'
  stderr_lines: <omitted>
  stdout: ''
  stdout_lines: <omitted>