Issue #28086: Single var-positional argument of tuple subtype was passed
unscathed to the C-defined function.  Now it is converted to exact tuple.
diff --git a/Python/ceval.c b/Python/ceval.c
index ff36d36..39cf330 100644
--- a/Python/ceval.c
+++ b/Python/ceval.c
@@ -3310,7 +3310,7 @@
             }
             callargs = POP();
             func = TOP();
-            if (!PyTuple_Check(callargs)) {
+            if (!PyTuple_CheckExact(callargs)) {
                 if (Py_TYPE(callargs)->tp_iter == NULL &&
                         !PySequence_Check(callargs)) {
                     PyErr_Format(PyExc_TypeError,
@@ -3327,7 +3327,7 @@
                     goto error;
                 }
             }
-            assert(PyTuple_Check(callargs));
+            assert(PyTuple_CheckExact(callargs));
 
             result = do_call_core(func, callargs, kwargs);
             Py_DECREF(func);