CLN: concat union_indexes now respecting sort keyword (#47588)

Author: phofl

pandas/core/frame.py

@@ -9523,7 +9523,6 @@ def _append(
  verify_integrity: bool = False,
  sort: bool = False,
  ) -> DataFrame:
- combined_columns = None
  if isinstance(other, (Series, dict)):
  if isinstance(other, dict):
  if not ignore_index:
@@ -9536,8 +9535,6 @@ def _append(
  )
 
  index = Index([other.name], name=self.index.name)
- idx_diff = other.index.difference(self.columns)
- combined_columns = self.columns.append(idx_diff)
  row_df = other.to_frame().T
  # infer_objects is needed for
  # test_append_empty_frame_to_series_with_dateutil_tz
@@ -9563,16 +9560,6 @@ def _append(
  verify_integrity=verify_integrity,
  sort=sort,
  )
- if (
- combined_columns is not None
- and not sort
- and not combined_columns.equals(result.columns)
- ):
- # TODO: reindexing here is a kludge bc union_indexes does not
- # pass sort to index.union, xref #43375
- # combined_columns.equals check is necessary for preserving dtype
- # in test_crosstab_normalize
- result = result.reindex(combined_columns, axis=1)
  return result.__finalize__(self, method="append")
 
  def join(