Accept None as start and stop parameters for list.index() and tuple.index().

Closes #13340.

diff --cc Lib/test/list_tests.py
Simple merge

diff --cc Misc/NEWS
index 06551c05b47bef57f73321ce5178a14bd42931a6,720fef3f7c570bfd3433c650d154863bab080129..1c81e321dfadc55c860da8ba0c6bfbc1ecd75c61
--- 1/Misc/NEWS
--- 2/Misc/NEWS
+++ b/Misc/NEWS
@@@ -10,8 -10,9 +10,11 @@@ What's New in Python 3.3 Alpha 1
  Core and Builtins
  -----------------
  
+ - Issue #13340: Accept None as start and stop parameters for
+   list.index() and tuple.index().
+ 
 +- Issue #9896: Add start, stop, and step attributes to range objects.
 +
  - Issue #13343: Fix a SystemError when a lambda expression uses a global
    variable in the default value of a keyword-only argument:
    (lambda *, arg=GLOBAL_NAME: None)

diff --cc Objects/listobject.c
Simple merge

diff --cc Objects/tupleobject.c
Simple merge