diff -r 4348fb8cae27 Lib/collections/__init__.py
--- a/Lib/collections/__init__.py   Fri May 27 12:56:41 2016 -0600
+++ b/Lib/collections/__init__.py   Sat May 28 00:20:55 2016 +0300
@@ -1085,6 +1085,7 @@
             self.data.extend(other.data)
         else:
             self.data.extend(other)
+    __copy__ = copy