Migration is disabled with "Migration over SSH disabled by TripleO" in /etc/nova/migration/identity in Red Hat OpenStack Platform 10

Issue

Migration fails with:

2018-10-17 20:42:20.482 272950 ERROR nova.servicegroup.drivers.db
2018-10-17 20:56:44.941 272950 ERROR nova.virt.libvirt.driver [req-10a9f46a-01b6-4662-8509-53d5b84e2bba 8bbfa086a13c48f88b9315716a04c6fb 9a83f2c3ca6448ef9587d7e3d2c4a43e - - -] [instance: 8c86d73d-2b70-4b6d-8b7f-ebf37720a44a] Live Migration failure: operation failed: Failed to connect to remote libvirt URI qemu+ssh://nova_migration@compute1.localdomain/system?keyfile=/etc/nova/migration/identity: Cannot recv data: Permission denied (publickey,gssapi-keyex,gssapi-with-mic).: Connection reset by peer
2018-10-17 20:56:45.516 272950 ERROR nova.virt.libvirt.driver [req-10a9f46a-01b6-4662-8509-53d5b84e2bba 8bbfa086a13c48f88b9315716a04c6fb 9a83f2c3ca6448ef9587d7e3d2c4a43e - - -] [instance: 8c86d73d-2b70-4b6d-8b7f-ebf37720a44a] Migration operation has aborted
2018-10-17 20:59:54.764 276111 DEBUG oslo_service.service [req-5c18f455-f51f-401a-8d7e-6bdea1dc2bef - - - - -] logging_exception_prefix       = %(asctime)s.%(msecs)03d %(process)d ERROR %(name)s %(instance)s log_opt_values /usr/lib/python2.7/site-packages/oslo_config/cfg.py:2622
2018-10-17 21:04:30.710 276111 ERROR nova.virt.libvirt.driver [req-560896c3-d36a-477e-a2bc-3ba5371fac6c 8bbfa086a13c48f88b9315716a04c6fb 9a83f2c3ca6448ef9587d7e3d2c4a43e - - -] [instance: 8c86d73d-2b70-4b6d-8b7f-ebf37720a44a] Live Migration failure: operation failed: Failed to connect to remote libvirt URI qemu+ssh://nova_migration@compute1.localdomain/system?keyfile=/etc/nova/migration/identity: Cannot recv data: Permission denied (publickey,gssapi-keyex,gssapi-with-mic).: Connection reset by peer
2018-10-17 21:04:31.304 276111 ERROR nova.virt.libvirt.driver [req-560896c3-d36a-477e-a2bc-3ba5371fac6c 8bbfa086a13c48f88b9315716a04c6fb 9a83f2c3ca6448ef9587d7e3d2c4a43e - - -] [instance: 8c86d73d-2b70-4b6d-8b7f-ebf37720a44a] Migration operation has aborted
(END)

Migration is disabled with message Migration over SSH disabled by TripleO:

[root@compute4 ~]# cat /etc/nova/migration/identity
# Migration over SSH disabled by TripleO
[root@compute4 ~]#
[root@compute4 ~]# grep ive_migration_uri /etc/nova/nova.conf
#live_migration_uri=<None>
live_migration_uri=qemu+ssh://nova_migration@%s/system?keyfile=/etc/nova/migration/identity
[root@compute4 ~]#