L3VPN: IPV6 entries not disappearing from FIB with dualstack VM.

IPV6 entries not disappearing from FIB with dualstack VM.

1. Create N1 with two subnet(IPv4) and (IPV6).
2. Create 2 ports with each subnet.
3. Create Router.
4. Add IPV6 subnet to Router and validate IPv6 entries observed in FIB. -->PASS
5. Add IPv4 subnet to Router and validate FIB. -->PASS.
6. Create L3VPN and associate Router to VPN. --> PASS
7. Delete IPV4 subnet from Router and validate FIB --> PASS
8. Delete IPV6 subnet from Router and validate FIB --> FAIL

cli>display fib
   RD       Prefix                NextHop               Label    Origin
   -------------------------------------------------------------------
   0bf23b31-e015-4c7e-87be-317c1665cef1  2001:db8:1111::1/128  0.0.0.0               103001   l
   0bf23b31-e015-4c7e-87be-317c1665cef1  2001:db8:1111:0:f816:3eff:fee8:2c03/128  192.168.113.10        103082   l
   0bf23b31-e015-4c7e-87be-317c1665cef1  2001:db8:1111:0:f816:3eff:fe70:99c2/128  192.168.113.11        103081   l
   0bf23b31-e015-4c7e-87be-317c1665cef1  2001:db8:1111:0:f816:3eff:fead:4dbe/128  192.168.113.12        103083   l
   0bf23b31-e015-4c7e-87be-317c1665cef1  2001:db8:1111:0:f816:3eff:fe10:5988/128  192.168.113.10        103084   l
   0bf23b31-e015-4c7e-87be-317c1665cef1  2001:db8:1111:0:f816:3eff:feaa:2d99/128  192.168.113.12        103085   l
   0bf23b31-e015-4c7e-87be-317c1665cef1  2001:db8:1111:0:f816:3eff:fe5d:14e2/128  192.168.113.11        103086   l

root@cic-1:~# neutron router-list

root@cic-1:~#

root@cic-1:~# neutron bgpvpn-list

root@cic-1:~#