BUG: resampling with NaT in TimedeltaIndex (#13223)

Author: paulgliu

pandas/tseries/resample.py

@@ -10,6 +10,8 @@
                                  SeriesGroupBy, groupby, PanelGroupBy,
                                  DataError)
 
+from pandas.tseries.frequencies import to_offset, is_subperiod, is_superperiod
+
 from pandas.tseries.frequencies import to_offset, is_subperiod, is_superperiod
 from pandas.tseries.index import DatetimeIndex, date_range
 from pandas.tseries.tdi import TimedeltaIndex
@@ -528,7 +530,7 @@ def asfreq(self):
         Series.asfreq
         DataFrame.asfreq
         """
-        return self._upsample('asfreq', fill_value=fill_value)
+        return self._upsample('asfreq')
 
     def std(self, ddof=1, *args, **kwargs):
         """