fixup! ENH: Parametrized CategoricalDtype

Author: TomAugspurger

pandas/core/indexes/base.py

@@ -2174,8 +2174,9 @@ def union(self, other):
             return other._get_consensus_name(self)
 
         # TODO: is_dtype_union_equal is a hack around
-        # 1. buggy joins with duplicates
-        # 2. CategoricalIndex lacking setops
+        # 1. buggy set ops with duplicates (GH #13432)
+        # 2. CategoricalIndex lacking setops (GH #10186)
+        # Once those are fixed, this workaround can be removed
         if not is_dtype_union_equal(self.dtype, other.dtype):
             this = self.astype('O')
             other = other.astype('O')