SF bug #425836:  Reference leak in filter().
Mark Hammond claimed that the iterized filter() forgot to decref the
iterator upon return.  He was right!
diff --git a/Python/bltinmodule.c b/Python/bltinmodule.c
index b647f3b..78e2f37 100644
--- a/Python/bltinmodule.c
+++ b/Python/bltinmodule.c
@@ -264,6 +264,7 @@
 	if (j < len && PyList_SetSlice(result, j, len, NULL) < 0)
 		goto Fail_result_it;
 
+	Py_DECREF(it);
 	return result;
 
 Fail_result_it: