keepalived fails to start after updating DVR-HA internal network MTU

We got an issue when keepalived stops to be running after update MTU on the internal network of the DVR-HA router.
It turned out that the keepalived config has an interface from qrouter-ns although the keepalived process itself is running in snat-ns.

Here is a simple demo on the latest master branch:
$ openstack network create net1
$ openstack subnet create sub1 --network net1 --subnet-range 192.168.100.0/24
$ openstack router create r1 --distributed --ha
$ openstack router add subnet r1 sub1

Keepalived process is running and the config looks like:

$ ps axf | grep -w pid.keepalived
...
 130250 ? S 0:00 \_ keepalived -P -f /opt/stack/data/neutron/ha_confs/f7df848f-f168-4305-8ba2-a31902bdbbfd/keepalived.conf -p /opt/stack/data/neutron/ha_confs/f7df848f-f168-4305-8ba2-a31902bdbbfd.pid.keepalived -r /opt/stack/data/neutron/ha_confs/f7df848f-f168-4305-8ba2-a31902bdbbfd.pid.keepalived-vrrp -D
$ cat /opt/stack/data/neutron/ha_confs/f7df848f-f168-4305-8ba2-a31902bdbbfd/keepalived.conf
global_defs {
    notification_email_from <email address hidden>
    router_id neutron
}
vrrp_instance VR_60 {
    state BACKUP
    interface ha-77ee55dc-5c
    virtual_router_id 60
    priority 50
    garp_master_delay 60
    nopreempt
    advert_int 2
    track_interface {
        ha-77ee55dc-5c
    }
    virtual_ipaddress {
        169.254.0.60/24 dev ha-77ee55dc-5c
    }
$

Now update MTU of the internal network:

$ openstack network set net1 --mtu 1400
$ ps axf | grep -w pid.keepalived
 131097 pts/0 S+ 0:00 | \_ grep --color=auto -w pid.keepalived
$

$ ip netns exec snat-f7df848f-f168-4305-8ba2-a31902bdbbfd keepalived -t -f /opt/stack/data/neutron/ha_confs/f7df848f-f168-4305-8ba2-a31902bdbbfd/keepalived.conf
(/opt/stack/data/neutron/ha_confs/f7df848f-f168-4305-8ba2-a31902bdbbfd/keepalived.conf: Line 20) WARNING - interface qr-035f8095-76 for ip address 192.168.100.1/24 doesn't exist
(/opt/stack/data/neutron/ha_confs/f7df848f-f168-4305-8ba2-a31902bdbbfd/keepalived.conf: Line 21) WARNING - interface qr-035f8095-76 for ip address fe80::f816:3eff:fe88:e922/64 doesn't exist
Non-existent interface specified in configuration
$
$ cat /opt/stack/data/neutron/ha_confs/f7df848f-f168-4305-8ba2-a31902bdbbfd/keepalived.conf
global_defs {
    notification_email_from <email address hidden>
    router_id neutron
}
vrrp_instance VR_60 {
    state BACKUP
    interface ha-77ee55dc-5c
    virtual_router_id 60
    priority 50
    garp_master_delay 60
    nopreempt
    advert_int 2
    track_interface {
        ha-77ee55dc-5c
    }
    virtual_ipaddress {
        169.254.0.60/24 dev ha-77ee55dc-5c
    }
    virtual_ipaddress_excluded {
        192.168.100.1/24 dev qr-035f8095-76
        fe80::f816:3eff:fe88:e922/64 dev qr-035f8095-76 scope link
    }
}$

$ ip netns exec snat-f7df848f-f168-4305-8ba2-a31902bdbbfd ip link
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
10: ha-77ee55dc-5c: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1450 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1000
    link/ether fa:16:3e:46:30:c4 brd ff:ff:ff:ff:ff:ff
$