Document change to PyTuple_SET_ITEM

Author: markshannon

Doc/whatsnew/3.13.rst

@@ -1872,6 +1872,10 @@ Porting to Python 3.13
   platforms, the ``HAVE_STDDEF_H`` macro is only defined on Windows.
   (Contributed by Victor Stinner in :gh:`108765`.)
 
+* The :c:func`PyTuple_SET_ITEM` inline function may not be passed ``NULL``.
+  This has always been the documented behavior, but was not enforced for
+  the value until now.
+
 Deprecated
 ----------
 

Include/internal/pycore_list.h

@@ -55,6 +55,7 @@ typedef struct {
 } _PyListIterObject;
 
 PyAPI_FUNC(PyObject *)_PyList_FromArraySteal(PyObject *const *src, Py_ssize_t n);
+
 /* Creates tuple from the list, leaving the list empty */
 PyObject *_PyList_AsTupleTakeItems(PyObject *);