message: fix(viz): time shift read-only error
diff: @@ -1362,8 +1362,10 @@ class NVD3TimeSeriesViz(NVD3Viz):
  df2 = self.get_df_payload(query_object, time_compare=option).get("df")
  if df2 is not None and DTTM_ALIAS in df2:
  + dttm_series = df2[DTTM_ALIAS] + delta
  + df2 = df2.drop(DTTM_ALIAS, axis=1)
  + df2 = pd.concat([dttm_series, df2], axis=1)
  label = "{} offset".format(option)
  - df2[DTTM_ALIAS] += delta
  df2 = self.process_data(df2)
  self._extra_chart_data.append((label, df2))
  