Owner review of the v0.19.0 demo + Cisco docs/real spine CLI verification:
ACI spines name the VLAN-4 sub-if after the PORT (eth1/49.49, cf.
Eth1/29.29-style in show ip ospf neighbors vrf overlay-1); the ISN Nexus
names its dot1q-4 sub-if after the VLAN (Ethernet1/1.4). v0.19.0 had the
two conventions swapped. 908 tests green.