Nova commit 322cc9336fe6f6fe9b3f0da33c6b26a3e5ea9b0c added the
neutron.allow_duplicate_networks config option in Juno and it defaults
to False. The option was deprecated in Kilo with commit
4306d9190f49e7fadf88669d18effedabc880d3b and removed in Liberty with
commit b06867c581541ed325ddc5e5b5a2d53b1b0261ac so it's the default
behavior in Liberty.
To test it in the gate with Tempest, we need to be able to set it to
True in devstack-gate and update tempest.conf (since tempest is branchless
and we don't want to try to test duplicate networks against kilo/juno code).
We can remove the change to lib/tempest when it's removed from Tempest
after kilo-eol.
Depends-On: I05f81d86cde249c23be06d5804fadbf40fc4a7f3
Change-Id: Ifd075420f57c9b60746f4a6af6520c0ef04800db
89ee585230