NULL and no exception set from tp_iternext means StopIteration

Lib/test/test_pep380.py

@@ -831,6 +831,11 @@ class TestPEP380Operation(unittest.TestCase):
             "Enter f",
         ])
 
+    def test_yield_from_empty(self):
+        def g():
+            yield from ()
+        self.assertRaises(StopIteration, next, g())
+
 
 def test_main():
     from test import support

Python/ceval.c

@@ -1839,7 +1839,8 @@ PyEval_EvalFrameEx(PyFrameObject *f, int throwflag)
             if (!retval) {
                 /* iter may be exhausted */
                 Py_CLEAR(x);
-                if (!PyErr_ExceptionMatches(PyExc_StopIteration)) {
+                if (PyErr_Occurred() &&
+                    !PyErr_ExceptionMatches(PyExc_StopIteration)) {
                     /* some other exception */
                     break;
                 }