Issue #28820: Merge typo fixes from 3.6

diff --cc Objects/abstract.c
index 8892e3ed52a3b8688f042f66e28ee30414cbf688,d838856d452872e714c5472c6b95303c43c1862a..8447fdbc24fe0d6515e2de81c7a1f4cfffdcf0c9
--- 1/Objects/abstract.c
--- 2/Objects/abstract.c
+++ b/Objects/abstract.c
@@@ -2331,10 -2325,9 +2331,10 @@@ exit
      return result;
  }
  
- /* Positional arguments are obj followed args:
 -/* Positional arguments are obj followed by args. */
++/* Positional arguments are obj followed by args:
 +   call callable(obj, *args, **kwargs) */
  PyObject *
 -_PyObject_Call_Prepend(PyObject *func,
 +_PyObject_Call_Prepend(PyObject *callable,
                         PyObject *obj, PyObject *args, PyObject *kwargs)
  {
      PyObject *small_stack[8];