Fix for SF bug 571885

When resizing a tuple, zero out the memory starting at the end of the
old tuple not at the beginning of the old tuple.
diff --git a/Objects/tupleobject.c b/Objects/tupleobject.c
index 525e8f6..4c264fd 100644
--- a/Objects/tupleobject.c
+++ b/Objects/tupleobject.c
@@ -696,8 +696,8 @@
 	_Py_NewReference((PyObject *) sv);
 	/* Zero out items added by growing */
 	if (newsize > oldsize)
-		memset(sv->ob_item, 0,
-			sizeof(*sv->ob_item) * (newsize - oldsize));
+		memset(&sv->ob_item[oldsize], 0,
+		       sizeof(*sv->ob_item) * (newsize - oldsize));
 	*pv = (PyObject *) sv;
 	_PyObject_GC_TRACK(sv);
 	return 0;