chucknull -> is_scalar + isna

pandas/core/indexes/base.py

@@ -3728,7 +3728,7 @@ def insert(self, loc, item):
         -------
         new_index : Index
         """
-        if lib.checknull(item):
+        if is_scalar(item) and isna(item):
             # GH 18295
             item = self._na_value
 

pandas/core/indexes/category.py

@@ -1,5 +1,5 @@
 import numpy as np
-from pandas._libs import index as libindex, lib
+from pandas._libs import index as libindex
 
 from pandas import compat
 from pandas.compat.numpy import function as nv
@@ -12,7 +12,7 @@
     is_scalar)
 from pandas.core.common import (_asarray_tuplesafe,
                                 _values_from_object)
-from pandas.core.dtypes.missing import array_equivalent
+from pandas.core.dtypes.missing import array_equivalent, isna
 from pandas.core.algorithms import take_1d
 
 
@@ -688,7 +688,7 @@ def insert(self, loc, item):
 
         """
         code = self.categories.get_indexer([item])
-        if (code == -1) and not lib.checknull(item):
+        if (code == -1) and not (is_scalar(item) and isna(item)):
             raise TypeError("cannot insert an item into a CategoricalIndex "
                             "that is not already an existing category")
 

pandas/core/indexes/datetimes.py

@@ -1751,7 +1751,7 @@ def insert(self, loc, item):
         -------
         new_index : Index
         """
-        if lib.checknull(item):
+        if is_scalar(item) and isna(item):
             # GH 18295
             item = self._na_value
 

pandas/core/indexes/interval.py

@@ -22,7 +22,7 @@
     Index, _ensure_index,
     default_pprint, _index_shared_docs)
 
-from pandas._libs import lib, Timestamp, Timedelta
+from pandas._libs import Timestamp, Timedelta
 from pandas._libs.interval import (
     Interval, IntervalMixin, IntervalTree,
     intervals_to_interval_bounds)
@@ -986,7 +986,7 @@ def insert(self, loc, item):
                                  'side as the index')
             left_insert = item.left
             right_insert = item.right
-        elif lib.checknull(item):
+        elif is_scalar(item) and isna(item):
             # GH 18295
             left_insert = right_insert = item
         else:

pandas/core/indexes/timedeltas.py

@@ -855,12 +855,12 @@ def insert(self, loc, item):
                 item = Timedelta(item)
             except Exception:
                 pass
-        elif lib.checknull(item):
+        elif is_scalar(item) and isna(item):
             # GH 18295
             item = self._na_value
 
         freq = None
-        if isinstance(item, Timedelta) or (item is self._na_value):
+        if isinstance(item, Timedelta) or (is_scalar(item) and isna(item)):
 
             # check freq can be preserved on edge cases
             if self.freq is not None: