Fix some references leaks in _pickle

Author: sergey-miryanov

Modules/_pickle.c

@@ -4725,6 +4725,7 @@ Pickler_clear(PicklerObject *self)
     Py_CLEAR(self->output_buffer);
     Py_CLEAR(self->write);
     Py_CLEAR(self->persistent_id);
+    Py_CLEAR(self->persistent_id_attr);
     Py_CLEAR(self->dispatch_table);
     Py_CLEAR(self->fast_memo);
     Py_CLEAR(self->reducer_override);
@@ -4754,6 +4755,7 @@ Pickler_traverse(PicklerObject *self, visitproc visit, void *arg)
     Py_VISIT(Py_TYPE(self));
     Py_VISIT(self->write);
     Py_VISIT(self->persistent_id);
+    Py_VISIT(self->persistent_id_attr);
     Py_VISIT(self->dispatch_table);
     Py_VISIT(self->fast_memo);
     Py_VISIT(self->reducer_override);
@@ -7227,6 +7229,7 @@ Unpickler_clear(UnpicklerObject *self)
     Py_CLEAR(self->peek);
     Py_CLEAR(self->stack);
     Py_CLEAR(self->persistent_load);
+    Py_CLEAR(self->persistent_load_attr);
     Py_CLEAR(self->buffers);
     if (self->buffer.buf != NULL) {
         PyBuffer_Release(&self->buffer);
@@ -7266,6 +7269,7 @@ Unpickler_traverse(UnpicklerObject *self, visitproc visit, void *arg)
     Py_VISIT(self->peek);
     Py_VISIT(self->stack);
     Py_VISIT(self->persistent_load);
+    Py_VISIT(self->persistent_load_attr);
     Py_VISIT(self->buffers);
     PyObject **memo = self->memo;
     if (memo) {