message: Ensure that dttm is of same timezone as epoch_with_tz
diff: @@ -358,6 +358,7 @@ def pessimistic_json_iso_dttm_ser(obj):
  def datetime_to_epoch(dttm):
  if dttm.tzinfo:
  + dttm = dttm.replace(tzinfo=pytz.utc)
  epoch_with_tz = pytz.utc.localize(EPOCH)
  return (dttm - epoch_with_tz).total_seconds() * 1000
  return (dttm - EPOCH).total_seconds() * 1000
  