pool with -X (sync). This is a case where the last vlan is removed
from a port, but not allowed to do that on a procurve. It has to be
added to vlan 1 first, and then the other removed. But the port is in
"dual" mode tagging, and because of the way that is implemented in
snmpit_hp, it was failing. The port has to be converted to equal
tagging first, then vlan 1 added, and then finally the actual vlan
removed.

Caveat; once we do this the port is in equal mode, and if were to add
a tagged vlan back to it, we would not be operating as before. But
this is not a use case we currently have.