fix a refleak in slot_sq_length (#1162)

diff --git a/Objects/typeobject.c b/Objects/typeobject.c
index 89fe82c7c39a7d8a72131e82a29c4c24abec3fa4..9eb725f062ba56259f94e4b7318c1854d91fc28f 100644 (file)
--- a/Objects/typeobject.c
+++ b/Objects/typeobject.c
@@ -5931,6 +5931,7 @@ slot_sq_length(PyObject *self)
 
     assert(PyLong_Check(res));
     if (Py_SIZE(res) < 0) {
+        Py_DECREF(res);
         PyErr_SetString(PyExc_ValueError,
                         "__len__() should return >= 0");
         return -1;