[docs] [issue21333] Document recommended exception for objects that shouldn't be pickled

Michael Crouch added the comment: When pickling an object fails on line 70 of copy_reg.py, a "TypeError" is raised. However, according to section 11.1.3 of the Standard Library documentation, when an unpicklable object is passed to the dump() method the "PicklingError" exception will be raised. ---------- components: +Library (Lib) -Documentation nosy: +Michael Crouch versions: +Python 2.7 -Python 3.5 _______________________________________ Python tracker <report@bugs.python.org> <http://bugs.python.org/issue21333> _______________________________________