Fix nit (sentinel on lhs of comparison).

Objects/iterobject.c

@@ -177,9 +177,7 @@ calliter_iternext(calliterobject *it)
         Py_DECREF(args);
         if (result != NULL) {
             int ok;
-            ok = PyObject_RichCompareBool(result,
-                                          it->it_sentinel,
-                                          Py_EQ);
+            ok = PyObject_RichCompareBool(it->it_sentinel, result, Py_EQ);               
             if (ok == 0)
                 return result; /* Common case, fast path */
             Py_DECREF(result);