Find auto-deploy intersection for Canonical deployments
Due to utilizing the merge train to keep Security
with Canonical, the latest deployed commit will usually only exist on
Security, so it can't be used for the Canonical deployment tracking.
Similarly for Omnibus, the deployed commit is usually an "Update
component versions" commit that only gets created in the auto-deploy
branch which, with
auto_deploy_on_security enabled, will only exist on
As a workaround, when creating a Security deployment we now find the latest commit that also exists on Canonical -- the intersection -- and use that for the deployment there.