using self._na_value instead of np.nan

Author: realead

pandas/core/indexes/numeric.py

@@ -118,7 +118,7 @@ def is_all_dates(self):
     def insert(self, loc, item):
         # treat NA values as nans:
         if is_scalar(item) and isna(item):
-            item = np.nan
+            item = self._na_value
         return super(NumericIndex, self).insert(loc, item)