This also manifests as nova-api being unable to start when running devstack.
To make matters worse, the logic for disabling the novnc install from packages is broken, which means novnc will always be installed from packages. The change I just proposed fixes that.
FWIW, I tried to make a similar change a few months ago to install novnc from packages and ran into similar problems. I feel like the deps in Ubuntu are just wrong - novnc should not depend on nova-common as far as I can tell. It's not an OpenStack project so it should be able to run without nova components installed.
This also manifests as nova-api being unable to start when running devstack.
To make matters worse, the logic for disabling the novnc install from packages is broken, which means novnc will always be installed from packages. The change I just proposed fixes that.
FWIW, I tried to make a similar change a few months ago to install novnc from packages and ran into similar problems. I feel like the deps in Ubuntu are just wrong - novnc should not depend on nova-common as far as I can tell. It's not an OpenStack project so it should be able to run without nova components installed.