bpo-35441: Remove dead and buggy code related to PyList_SetItem(). (GH-11033)


In _localemodule.c and selectmodule.c, remove dead code that would
cause double decrefs if run.

In addition, replace PyList_SetItem() with PyList_SET_ITEM() in cases
where a new list is populated and there is no possibility of an error.

In addition, check if the list changed size in the loop in array_array_fromlist().
(cherry picked from commit 99d56b53560b3867844472ae381fb3f858760621)

Co-authored-by: Zackery Spytz <zspytz@gmail.com>
diff --git a/Modules/selectmodule.c b/Modules/selectmodule.c
index 88679e8..93d896a 100644
--- a/Modules/selectmodule.c
+++ b/Modules/selectmodule.c
@@ -652,10 +652,7 @@
             goto error;
         }
         PyTuple_SET_ITEM(value, 1, num);
-        if ((PyList_SetItem(result_list, j, value)) == -1) {
-            Py_DECREF(value);
-            goto error;
-        }
+        PyList_SET_ITEM(result_list, j, value);
         i++;
     }
     return result_list;
@@ -981,10 +978,7 @@
         Py_DECREF(num2);
         if (value == NULL)
             goto error;
-        if ((PyList_SetItem(result_list, i, value)) == -1) {
-            Py_DECREF(value);
-            goto error;
-        }
+        PyList_SET_ITEM(result_list, i, value);
     }
 
     return result_list;