Issue 18159 review applied

doc/source/whatsnew/v0.21.1.txt

@@ -56,15 +56,7 @@ Documentation Changes
 
 Bug Fixes
 ~~~~~~~~~
-- Bug in ``DataFrame.resample(...).apply(...)`` when there is a callable that returns different columns (:issue:`15169`)
-- Bug in :class:`TimedeltaIndex` subtraction could incorrectly overflow when ``NaT`` is present (:issue:`17791`)
-- Bug in :class:`DatetimeIndex` subtracting datetimelike from DatetimeIndex could fail to overflow (:issue:`18020`)
-- Bug in ``pd.Series.rolling.skew()`` and ``rolling.kurt()`` with all equal values has floating issue (:issue:`18044`)
-- Bug in ``pd.DataFrameGroupBy.count()`` when counting over a datetimelike column (:issue:`13393`)
-- Bug in ``pd.concat`` when empty and non-empty DataFrames or Series are concatenated (:issue:`18178` :issue:`18187`)
-- Bug in :class:`IntervalIndex` constructor when a list of intervals is passed with non-default ``closed`` (:issue:`18334`)
-- Bug in :meth:`IntervalIndex.copy` when copying and ``IntervalIndex`` with non-default ``closed`` (:issue:`18339`)
-- Bug in :meth:`fillna` maximum recursion depth exceeded in cmp (:issue:`18159`).
+- Bug in :meth:`fillna` where maximum recursion depth gets exceeded in comparison (:issue:`18159`).
 
 
 Conversion

pandas/core/internals.py

@@ -1848,7 +1848,7 @@ def _can_hold_element(self, element):
             return (issubclass(tipo.type, (np.floating, np.integer)) and
                     not issubclass(tipo.type, (np.datetime64, np.timedelta64)))
         return (
-            isinstance(element, (float, int, np.floating, np.int_, np.long))
+            isinstance(element, (float, int, np.floating, np.int_, compat.long))
             and not isinstance(element, (bool, np.bool_, datetime, timedelta,
                                          np.datetime64, np.timedelta64)))