NetworkManager doesn't always set the hostname when DHCP6 is involved. This sets the hostname when $DHCP6_FQDN_FQDN is populated and does not equal localhost.localdomain. This is a workaround while we try to figure out why NetworkManager is not setting the hostname as it should.
Since the problem described in this bug report should be resolved in a recent advisory, it has been closed with a resolution of ERRATA. For information on the advisory (OpenShift Container Platform 4.5 image release advisory), and where to find the updated files, follow the link below. If the solution does not work for you, open a new bug report. https://access.redhat.com/errata/RHBA-2020:2409