// If rollback revision is 0, rollback to the last revision
	if rollbackTo.Revision == 0 {
		if rollbackTo.Revision = deploymentutil.LastRevision(logger, allRSs); rollbackTo.Revision == 0 {
			// If we still can't find the last revision, gives up rollback
			dc.emitRollbackWarningEvent(d, deploymentutil.RollbackRevisionNotFound, "Unable to find last revision.")
			// Gives up rollback
			return dc.updateDeploymentAndClearRollbackTo(ctx, d)