os-net-config fails to provision networking configuration if one of OVS bond's slaves is down

Issue

Overcloud deployment/scale-out fails because os-net-config is unable to provision OVS bond when its slave link is down.

Jun  2 13:25:58 compute-01.example.com os-collect-config: Command: /bin/ovs-appctl bond/set-active-slave bond1 eno1
Jun  2 13:25:58 compute-01.example.com os-collect-config: Exit code: 2
Jun  2 13:25:58 compute-01.example.com os-collect-config: Stdout: u''
Jun  2 13:25:58 compute-01.example.com os-collect-config: Stderr: u'cannot make disabled slave active\novs-appctl: ovs-vswitchd: server returned an error\n'
Jun  2 13:25:58 compute-01.example.com os-collect-config: + RETVAL=1
Jun  2 13:25:58 compute-01.example.com os-collect-config: + set -e
Jun  2 13:25:58 compute-01.example.com os-collect-config: + [[ 1 == 2 ]]
Jun  2 13:25:58 compute-01.example.com os-collect-config: + [[ 1 != 0 ]]
Jun  2 13:25:58 compute-01.example.com os-collect-config: + echo 'ERROR: os-net-config configuration failed.'