Pickling a dictionary

[Devashish Tyagi]

So I want to store the current state of a InteractiveInterpreter Object in database. In order to achieve this I tried this

obj = InteractiveInterpreter()
local = obj.locals()
pickle.dump(local, open('obj.dump','rw'))

But I received an error say 
TypeError: can't pickle ellipsis objects

>From what I understand this shouldn't occur as local is a dictionary. Any particular reason for this behaviour?