We currently have state and state_reason for ArtifactBuild, but not for Event. But if there is no ArtifactBuild to be built for particular Event, then we don't know if it was Freshmaker issue or the event was successfully handled and there are just no artifacts to be rebuilt.

Things to do:

• Add state and state_reason to Event.
• Set state and state_reason in Event.builds_transition().
• Add Event.transition(state, state_reason) which just sets the Event.state and Event.state_reason without setting state/state_reason of ArtifactBuilds and use it in case when no container images are found for a build here: https://pagure.io/freshmaker/blob/master/f/freshmaker/handlers/errata/errata_advisory_rpms_signed.py#_90