mgmt_snapshot_user-lts has as downstream mgmt_build_xenial_release which means it anchors on the wrong job, meaning it deadlocks with a release-lts build which wants to run _pub but mgmt_snapshot_user-lts is already running (which counts as a publisher as it needs to lock the repo for the duration of the snapshot) but then the mgmt_daily_promotion_xenial_release-lts job can't start because the _pub needs to run, but the _pub can't run because mgmt_snapshot_user-lts is running and mgmt_snapshot_user-lts cannot proceed because mgmt_daily_promotion_xenial_release-lts is blocked.

mgmt_snapshot_user-lts -> mgmt_daily_promotion_xenial_release-lts -> *_pub -> mgmt_snapshot_user-lts -> mgmt_daily_promotion_xenial_release-lts -> *_pub -> ...

mgmt_snapshot_user-lts needs mgmt_build_xenial_release-lts as downstream