Commit a97627ac513c1775c656fdb4b6acdec8b4de2f05 caused a
degradation with external network creation. Prior to this
patch a external network could be created in horizon with
type 'local.
That support needs to be continued for backwards compatibility.
Change-Id: Id0e891842c1d4e63c522a82b09beeeeca6fdbb7b