message: [Fix] merge since,until request parameter with time_range
diff: @@ -1033,6 +1033,15 @@ class Superset(BaseSupersetView):
  slc = db.session.query(models.Slice).filter_by(id=slice_id).first()
  slice_form_data = slc.form_data.copy()
  # allow form_data in request override slice from_data
  + # special treat for since/until and time_range parameter:
  + # we need to breakdown time_range into since/until so request parameters
  + # has precedence over slice parameters for time fields.
  + if 'time_range' in form_data:
  + form_data['since'], separator, form_data['until'] = \
  + form_data['time_range'].partition(' : ')
  + if 'time_range' in slice_form_data:
  + slice_form_data['since'], separator, slice_form_data['until'] = \
  + slice_form_data['time_range'].partition(' : ')
  slice_form_data.update(form_data)
  form_data = slice_form_data
  