switch to icehouse -> juno upgrade

make nova rolling upgrade use base release

instead of hard coding this, always use the base release value.
This will let us roll forward gracefully in the future.

Related-Bug: #1309324

Change-Id: If9417e65c7c54d017c4c847a4020f855684c423c
Fix error message in upgrade_project()

It's not just for Cinder...

Change-Id: I285279f5e8f4b414d75be80776a039fa98dbe5c8
Merge "switch to icehouse -> juno upgrade"
Configure VPN when upgrading from Icehouse

There was a change in devstack how VPNaaS agent is started. It uses some
global variables introduced by https://review.openstack.org/#/c/86567/

Closes-Bug: #1313791
Change-Id: I76d8e8c9b9ac558f31cb3e22a936efbebff5b9a3
make the exit trap only dump on fail

We should only dump things like the process list on a failure,
not all the time.

Change-Id: Ibf6edbeedb2fdd76ee59d3908bf1991873c5e5a3
Merge "Configure VPN when upgrading from Icehouse"