Comment 1 for bug 1471316

My undestanding of expected behavior is a bit different here.
If value for default_ipv4_subnet_pool or default_ipv6_subnet_pool are set in config,
then all subnet allocations are expected to be done using subnet_pool,
independently whether cidr is set (specific subnet) or not (auto subnet).

Need to check with Ryan Tidwell and Carl Baldween to confirm expected behavior here,
because they know subnetpool stuff better.

At first I thought [1] caused this issue, but after double checking
I didn't notice any change is handling subnetpool_id.
I.e. _get_subnetpool_id always returned default subnet_pool if it is set in config (independently from presence of cidr)

[1] https://review.openstack.org/#/c/197090/