First, the nullable attribute on port_id was redundant because it is
in the primary key.
Second, trunk_id shouldn't be in the primary key. Since port_id was
already marked unique, it didn't add any extra uniqueness constraint
and it doesn't help to have it in a primary key index either since
we'll either search the table for a given port_id *or* search for
subports with a given trunk_id.
The original model was not released in Mitaka. Also, this is
effectively a cosmetic change, it doesn't really effect the operation
of the DB. So, developers and trunk chasers who have deployed with
the previous model will still work.
Change-Id: Ia43a2a772f654e26c3234e153fd8a5501e585c9b
Partially-Implements: blueprint vlan-aware-vms
eb0861135b