Fix comment

Author: erikoveson

pandas/core/arrays/categorical.py

@@ -348,8 +348,8 @@ def __init__(self, values, categories=None, ordered=None, dtype=None,
             dtype = values.dtype._from_categorical_dtype(values.dtype,
                                                          categories, ordered)
 
-            # GH23814, for perf, if no optional params used and values already
-            # an instance of Categorical, set values to codes like fastpath
+            # GH23814, for perf, if values._values already an instance of
+            # Categorical, set values to codes, and run fastpath
             if (isinstance(values, (ABCSeries, ABCIndexClass)) and
                isinstance(values._values, type(self))):
                 values = values._values.codes.copy()