Updating single segment networks created with this
module failed with:
"Cannot update provider:physical_network in
Single segment networks have the physical_network
set at the network level. For multi-segment networks
the physical_network is only set on the segments.
Due to the incremental addition of support for multiple
segments in THT the nameing convention for the base
segment and additional segments are not identical.
This change relaxes the test for physical_network
change not allowed so that it accepts both naming