- Update to 0.24.1
* The default ``sort`` value for :meth:`Index.union` has changed from ``True`` to ``None`` (:issue:`24959`).
The default *behavior*, however, remains the same
* Fixed regression in :meth:`DataFrame.to_dict` with ``records`` orient raising an
``AttributeError`` when the ``DataFrame`` contained more than 255 columns, or
wrongly converting column names that were not valid python identifiers (:issue:`24939`, :issue:`24940`).
* Fixed regression in :func:`read_sql` when passing certain queries with MySQL/pymysql (:issue:`24988`).
* Fixed regression in :class:`Index.intersection` incorrectly sorting the values by default (:issue:`24959`).
* Fixed regression in :func:`merge` when merging an empty ``DataFrame`` with multiple timezone-aware columns on one of the timezone-aware columns (:issue:`25014`).
* Fixed regression in :meth:`Series.rename_axis` and :meth:`DataFrame.rename_axis` where passing ``None`` failed to remove the axis name (:issue:`25034`)
* Fixed regression in :func:`to_timedelta` with `box=False` incorrectly returning a ``datetime64`` object instead of a ``timedelta64`` object (:issue:`24961`)
* Fixed regression where custom hashable types could not be used as column keys in :meth:`DataFrame.set_index` (:issue:`24969`)
* Bug in :meth:`DataFrame.groupby` with :class:`Grouper` when there is a time change (DST) and grouping frequency is ``'1d'`` (:issue:`24972`)
* Fixed the warning for implicitly registered matplotlib converters not showing. See :ref:`whatsnew_0211.converters` for more (:issue:`24963`).
* Fixed AttributeError when printing a DataFrame's HTML repr after accessing the IPython config object (:issue:`25036`)