Fix minor subclassing issue with collections.Counter
diff --git a/Lib/collections.py b/Lib/collections.py
index 27bb5e1..30301ce 100644
--- a/Lib/collections.py
+++ b/Lib/collections.py
@@ -459,8 +459,8 @@
             self.update(kwds)
 
     def copy(self):
-        'Like dict.copy() but returns a Counter instance instead of a dict.'
-        return Counter(self)
+        'Return a shallow copy.'
+        return self.__class__(self)
 
     def __reduce__(self):
         return self.__class__, (dict(self),)