Flow entries installed for SG remains after delete of rules also

the below CSIT link indicates that the table:39 flows that are installed for security groups are not deleted even after the VM instances are deleted.

https://logs.opendaylight.org/releng/jenkins092/netvirt-legacy-csit-1node-openstack-mitaka-upstream-boron/43/archives/log.html.gz#s1-s1-t26-k3-k1-k2-k1-k15-k3

Steps to recreate

a. Use Boron SR1
b. Create NEtwork/Subnet
c. Create VM instances
d. Add rule to allow icmp
e. ping the vm from dhcp NS
f. Delet VM instance
g. Delete rules

h. Check flow entries, the table=39 entries must be still remaining.