diff -r 60f5091cbfbf Objects/genobject.c
--- a/Objects/genobject.c	Sun May 31 11:28:57 2015 -0400
+++ b/Objects/genobject.c	Fri Jun 12 07:32:23 2015 +0200
@@ -465,7 +465,16 @@
                 Py_DECREF(ev);
             } else if (et == PyExc_StopIteration) {
                 /* avoid normalisation and take ev as value */
-                value = ev;
+                if (PyTuple_Check(ev)) {
+                    /* argument tuple, see PyErr_NormalizeException() */
+                    if (PyTuple_GET_SIZE(ev) > 0) {
+                        value = PyTuple_GET_ITEM(ev, 0);
+                        Py_INCREF(value);
+                    }
+                    Py_DECREF(ev);
+                } else {
+                    value = ev;
+                }
             } else {
                 /* normalisation required */
                 PyErr_NormalizeException(&et, &ev, &tb);