commit 0296a565205651b60a3a5690432beb6f3333a7fc
author Benjamin Peterson <benjamin@python.org> Fri Jan 13 14:54:31 2012 -0500
committer Benjamin Peterson <benjamin@python.org> Fri Jan 13 14:54:31 2012 -0500
tree a0341f20773fab2e74c99a0b328743d29270cb3a
parent 9a80fa81b0195bb744f89565bbc212d39c300942

NULL and no exception set from tp_iternext means StopIteration

Python/ceval.c

diff --git a/Python/ceval.c b/Python/ceval.c
index 134d1ee..98219b0 100644
--- a/Python/ceval.c
+++ b/Python/ceval.c
@@ -1839,7 +1839,8 @@
             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;
                 }