There is at least one other place (do_break) where this same problem could crop up.  Unittest handles this by having a 'safe_repr' function.  pdb doesn't need the same function unittest does, but it could do something similar, and then use %s and this function in the places where it currently uses repr to print an arbitrary object:

    def safe_repr(obj):
        try:
            return repr(obj)
        except Exception:
            return object.__repr__(obj)