Index: shelve.py
===================================================================
--- shelve.py	(revision 46688)
+++ shelve.py	(working copy)
@@ -142,6 +142,8 @@
         self.close()
 
     def sync(self):
+        if not hasattr(self, 'writeback'): 
+            return 
         if self.writeback and self.cache:
             self.writeback = False
             for key, entry in self.cache.iteritems():