Openstack undercloud upgrade/installation on 16.2 fails when undercloud public host and local IP values coincide

Issue

• The FQDN undercloud_public_host value is resolved to the local_ip value in /home/stack/undercloud.conf:

  [DEFAULT]
  local_ip = <local IP address>
  undercloud_public_host = <public host FQDN> #resolved into <local IP address>
  undercloud_admin_host = <admin VIP>
  

• The installation/upgrade process gets stuck at step 3 with the following logs:

  ERROR aodh oslo_db.exception.DBConnectionError: (pymysql.err.OperationalError (2003, "Can't connect to MySQL server on '<admin VIP>' ([Errno 113] No route to host)")