DB schema generated by a migration may look different in rails 4 and 5 (because rails 5 may use different default values). For this reason it's important to explicitly set for which rails version a migration was written for. See https://stackoverflow.com/questions/35929869/activerecordmigration-deprecation-warning-asks-for-rails-version-but-im-no/35930912#35930912
Not only tracking auto-cancelling in pipelines, we'll also track this in jobs because pipelines could be retried and the information would get lost when this happened. Also erase auto-cancelling relation for pipelines when they're retried.