pass through dtype

Author: TomAugspurger

pandas/core/indexes/category.py

@@ -159,16 +159,18 @@ def _simple_new(cls, values, name=None, categories=None, ordered=None,
 
     @Appender(_index_shared_docs['_shallow_copy'])
     def _shallow_copy(self, values=None, categories=None, ordered=None,
-                      **kwargs):
+                      dtype=None, **kwargs):
         # categories and ordered can't be part of attributes,
         # as these are properties
         if categories is None:
             categories = self.categories
         if ordered is None:
             ordered = self.ordered
-        return super(CategoricalIndex,
-                     self)._shallow_copy(values=values, categories=categories,
-                                         ordered=ordered, **kwargs)
+        if dtype is None:
+            dtype = self.dtype
+        return super(CategoricalIndex, self)._shallow_copy(
+            values=values, categories=categories,
+            ordered=ordered, dtype=dtype, **kwargs)
 
     def _is_dtype_compat(self, other):
         """