Comment 12 for bug 1823314

I think that I know what is going on there.

It is race condition with creating HA network and assigning new vr_id to the router.

Lets assume we are creating 2 different routers (first 2 HA routers for tenant).
Each request goes to different controller and now.
1. Controller-1, as part of creation of router-1, creates HA network, lets call it HA-Net-A,
2. For some reason (I'm not sure what the reason was exactly), controller-1 starts to remove HA-Net-A but
3. in same time on controller 2 HA-Net-A was found and router-2 is trying to use it
4. controller-2 allocates vr_id=1 for router-2 on HA-Net-A,
5. HA-Net-A is finally removed on controller-1 so controller-2 also got some error and retries configure router-2,
6. controller-2 creates new network HA-Net-B but it already have allocated vr_id=1 for router-2 (see p.4), it is stored in different table in db and have nothing to do with removed network,
7. controller-1 tries to allocate vr_id for router-1. As it is for HA-Net-B this time, vr_id=1 is free on this network so it is allocated,

And finally both routers got vr_id=1 allocated and only one of them is active on one L3 agent.