Reads all cron job runs for a given job id.

def ReadCronJobRuns(self, job_id, cursor=None):
    """Reads all cron job runs for a given job id."""
    query = """
    SELECT run, UNIX_TIMESTAMP(write_time)
      FROM cron_job_runs
     WHERE job_id = %s
    """
    cursor.execute(query, [job_id])
    runs = [self._CronJobRunFromRow(row) for row in cursor.fetchall()]
    return sorted(runs, key=lambda run: run.started_at, reverse=True)