diff -r d989abe6a2ad Lib/http/cookies.py
--- a/Lib/http/cookies.py	Wed Oct 29 10:57:37 2014 +0100
+++ b/Lib/http/cookies.py	Wed Oct 29 12:21:04 2014 +0100
@@ -486,6 +486,9 @@ class BaseCookie(dict):
 
     def __setitem__(self, key, value):
         """Dictionary style assignment."""
+        if isinstance(value, Morsel):
+            # allow assignment of constructed Morsels (e.g. for pickling)
+            dict.__setitem__(self, key, value)
         rval, cval = self.value_encode(value)
         self.__set(key, rval, cval)