neutron-openvswitch-agent reports `Transaction causes multiple rows in \"Manager\" table to have identical values` in Red Hat OpenStack Platform 11

Issue

neutron-openvswitch-agent reports Transaction causes multiple rows in \"Manager\" table to have identical values in Red Hat OpenStack Platform 11

[root@overcloud-controller-0 ~]# journalctl -u neutron-openvswitch-agent -f &
[1] 906189
[root@overcloud-controller-0 ~]# -- Logs begin at Tue 2017-10-24 01:32:42 UTC. --
Oct 24 17:39:20 overcloud-controller-0.localdomain neutron-openvswitch-agent[648103]: Guru meditation now registers SIGUSR1 and SIGUSR2 by default for backward compatibility. SIGUSR1 will no longer be registered in a future release, so please use SIGUSR2 to generate reports.
Oct 24 17:39:21 overcloud-controller-0.localdomain neutron-openvswitch-agent[648103]: Option "verbose" from group "DEFAULT" is deprecated for removal.  Its value may be silently ignored in the future.
Oct 24 17:39:21 overcloud-controller-0.localdomain neutron-openvswitch-agent[648103]: Option "rpc_backend" from group "DEFAULT" is deprecated for removal.  Its value may be silently ignored in the future.
Oct 24 17:39:21 overcloud-controller-0.localdomain neutron-openvswitch-agent[648103]: Option "notification_driver" from group "DEFAULT" is deprecated. Use option "driver" from group "oslo_messaging_notifications".
Oct 24 17:39:21 overcloud-controller-0.localdomain neutron-openvswitch-agent[648103]: Could not load neutron.openstack.common.notifier.rpc_notifier
Oct 24 17:39:26 overcloud-controller-0.localdomain neutron-openvswitch-agent[648103]: /usr/lib/python2.7/site-packages/oslo_messaging/rpc/server.py:200: FutureWarning: The access_policy argument is changing its default value to <class 'oslo_messaging.rpc.dispatcher.DefaultRPCAccessPolicy'> in version '?', please update the code to explicitly set None as the value: access_policy defaults to LegacyRPCAccessPolicy which exposes private methods. Explicitly set access_policy to DefaultRPCAccessPolicy or ExplicitRPCAccessPolicy.
Oct 24 17:39:26 overcloud-controller-0.localdomain neutron-openvswitch-agent[648103]: access_policy)
Oct 24 17:39:27 overcloud-controller-0.localdomain sudo[648766]:  neutron : TTY=unknown ; PWD=/ ; USER=root ; COMMAND=/bin/neutron-rootwrap-daemon /etc/neutron/rootwrap.conf
Oct 24 17:39:28 overcloud-controller-0.localdomain ovs-vsctl[648874]: ovs|00001|vsctl|INFO|Called as /bin/ovs-vsctl --timeout=10 --oneline --format=json -- --id=@manager create Manager "target=\"ptcp:6640:127.0.0.1\"" -- add Open_vSwitch . manager_options @manager
Oct 24 17:39:28 overcloud-controller-0.localdomain ovs-vsctl[648874]: ovs|00002|db_ctl_base|ERR|transaction error: {"details":"Transaction causes multiple rows in \"Manager\" table to have identical values (\"ptcp:6640:127.0.0.1\") for index on column \"target\".  First row, with UUID 3dba7961-9267-4551-8a55-42ae74a0902c, existed in the database before this transaction and was not modified by the transaction.  Second row, with UUID dae3fb03-ddef-44fb-a4ee-54ef256eef0a, was inserted by this transaction.","error":"constraint violation"}

[root@overcloud-controller-0 ~]# 
[root@overcloud-controller-0 ~]# systemctl restart neutron-openvswitch-agent
Oct 25 14:43:34 overcloud-controller-0.localdomain systemd[1]: Stopping OpenStack Neutron Open vSwitch Agent...
Oct 25 14:43:35 overcloud-controller-0.localdomain systemd[1]: Starting OpenStack Neutron Open vSwitch Agent...
Oct 25 14:43:35 overcloud-controller-0.localdomain neutron-enable-bridge-firewall.sh[906643]: net.bridge.bridge-nf-call-arptables = 1
Oct 25 14:43:35 overcloud-controller-0.localdomain neutron-enable-bridge-firewall.sh[906643]: net.bridge.bridge-nf-call-iptables = 1
Oct 25 14:43:35 overcloud-controller-0.localdomain neutron-enable-bridge-firewall.sh[906643]: net.bridge.bridge-nf-call-ip6tables = 1
Oct 25 14:43:35 overcloud-controller-0.localdomain systemd[1]: Started OpenStack Neutron Open vSwitch Agent.
[root@overcloud-controller-0 ~]# Oct 25 14:43:36 overcloud-controller-0.localdomain neutron-openvswitch-agent[906649]: Guru meditation now registers SIGUSR1 and SIGUSR2 by default for backward compatibility. SIGUSR1 will no longer be registered in a future release, so please use SIGUSR2 to generate reports.
Oct 25 14:43:36 overcloud-controller-0.localdomain neutron-openvswitch-agent[906649]: Option "verbose" from group "DEFAULT" is deprecated for removal.  Its value may be silently ignored in the future.
Oct 25 14:43:36 overcloud-controller-0.localdomain neutron-openvswitch-agent[906649]: Option "rpc_backend" from group "DEFAULT" is deprecated for removal.  Its value may be silently ignored in the future.
Oct 25 14:43:36 overcloud-controller-0.localdomain neutron-openvswitch-agent[906649]: Option "notification_driver" from group "DEFAULT" is deprecated. Use option "driver" from group "oslo_messaging_notifications".
Oct 25 14:43:36 overcloud-controller-0.localdomain neutron-openvswitch-agent[906649]: Could not load neutron.openstack.common.notifier.rpc_notifier
Oct 25 14:43:38 overcloud-controller-0.localdomain neutron-openvswitch-agent[906649]: /usr/lib/python2.7/site-packages/oslo_messaging/rpc/server.py:200: FutureWarning: The access_policy argument is changing its default value to <class 'oslo_messaging.rpc.dispatcher.DefaultRPCAccessPolicy'> in version '?', please update the code to explicitly set None as the value: access_policy defaults to LegacyRPCAccessPolicy which exposes private methods. Explicitly set access_policy to DefaultRPCAccessPolicy or ExplicitRPCAccessPolicy.
Oct 25 14:43:38 overcloud-controller-0.localdomain neutron-openvswitch-agent[906649]: access_policy)
Oct 25 14:43:39 overcloud-controller-0.localdomain sudo[907145]:  neutron : TTY=unknown ; PWD=/ ; USER=root ; COMMAND=/bin/neutron-rootwrap-daemon /etc/neutron/rootwrap.conf
Oct 25 14:43:39 overcloud-controller-0.localdomain ovs-vsctl[907157]: ovs|00001|vsctl|INFO|Called as /bin/ovs-vsctl --timeout=10 --oneline --format=json -- --id=@manager create Manager "target=\"ptcp:6640:127.0.0.1\"" -- add Open_vSwitch . manager_options @manager
Oct 25 14:43:39 overcloud-controller-0.localdomain ovs-vsctl[907157]: ovs|00002|db_ctl_base|ERR|transaction error: {"details":"Transaction causes multiple rows in \"Manager\" table to have identical values (\"ptcp:6640:127.0.0.1\") for index on column \"target\".  First row, with UUID 13742552-2c38-4af7-b7b7-da093ea8fdc5, was inserted by this transaction.  Second row, with UUID 3dba7961-9267-4551-8a55-42ae74a0902c, existed in the database before this transaction and was not modified by the transaction.","error":"constraint violation"}

[root@overcloud-controller-0 ~]# 
[root@overcloud-controller-0 ~]# 
[root@overcloud-controller-0 ~]# fg
journalctl -u neutron-openvswitch-agent -f
^C
[root@overcloud-controller-0 ~]# ^C
[root@overcloud-controller-0 ~]# ovs-vsctl list Manager
_uuid               : 3dba7961-9267-4551-8a55-42ae74a0902c
connection_mode     : []
external_ids        : {}
inactivity_probe    : 10000
is_connected        : true
max_backoff         : []
other_config        : {}
status              : {bound_port="6640", n_connections="3", sec_since_connect="0", sec_since_disconnect="0"}
target              : "ptcp:6640:127.0.0.1"
[root@overcloud-controller-0 ~]#