VDNS deletion successful even if it has other dependant VDNS servers

[Pulkit Tandon]

BUG Template : Ubuntu

OS version: 3.13.0-40-generic #69-Ubuntu
Contrail Version: 3.0.2.0-32

Setup details:
Multi node setup.

Configurations and Description:
This test creates 3 vnds servers vdns1,vdns2 and vdns3. For vdns2 and vdns3, vdns1 act a next vdns nerver.
The VDNS server are configured as shown below.
                                vdns1 (domain: juniper.net)
                               ^ ^
                              / \
                             / \
            (bng.juniper.net) vdns2 vdns3(eng.juniper.net)

Try to delete vdns entry which was referenced in other vdns entry expecting it to fail(vdns1)
Deletion of vdns1 is successful even if it has back references.

Same test step used to pass in earlier release R2.20.

[Kumar Harsh (hkumar)]

Not able to see this in latest build .

Build 2740 (kilo ubuntu14)