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
Previously, the last push widget would only show when the branch never had a merge request associated with it - even merged or closed ones. Now the widget will disregard merge requests that are merged or closed.