Comment 4 for bug 1578878

Zuul aborts builds by events 'patchset-created' and 'change-abandoned', but keywords in comments emit event 'comment-added'.

Code from Zuul's scheduler:

                if event.type == 'patchset-created':
                    pipeline.manager.removeOldVersionsOfChange(change)
                elif event.type == 'change-abandoned':
                    pipeline.manager.removeAbandonedChange(change)
                if pipeline.manager.eventMatches(event, change):
                    self.log.info("Adding %s, %s to %s" %
                                  (project, change, pipeline))
                    pipeline.manager.addChange(change)