Use series._values

TomAugspurger · TomAugspurger · commit d15a72270785 · 2018-01-27T19:08:37.000+01:00
diff --git a/pandas/core/dtypes/common.py b/pandas/core/dtypes/common.py
@@ -1713,7 +1713,7 @@ def is_extension_array_dtype(arr_or_dtype):
 
     # we want to unpack series, anything else?
     if isinstance(arr_or_dtype, ABCSeries):
-        arr_or_dtype = arr_or_dtype.values
+        arr_or_dtype = arr_or_dtype._values
     return isinstance(arr_or_dtype, (ExtensionDtype, ExtensionArray))
 
 
