update comments for _adjust_binner_for_upsample

Author: discort

pandas/core/resample.py

@@ -962,7 +962,10 @@ def _downsample(self, how, **kwargs):
  return self._wrap_result(result)
 
  def _adjust_binner_for_upsample(self, binner):
- """ adjust our binner when upsampling """
+ """
+ Adjust our binner when upsampling.
+ The range of a new index should not be outside specified range
+ """
  if self.closed == 'right':
  binner = binner[1:]
  else:
@@ -1156,6 +1159,7 @@ def _get_binner_for_time(self):
 
  def _adjust_binner_for_upsample(self, binner):
  """ adjust our binner when upsampling """
+ # Just returning binner directly, GH 13022
  return binner