tests: add missing import

git-svn-id: https://svn.erp5.org/repos/neo/trunk@2667 71dcc9de-d417-0410-9af5-da40c76e7ee4

neo/tests/functional/__init__.py

@@ -22,6 +22,7 @@ import ZODB
 import socket
 import signal
 import random
+import weakref
 import MySQLdb
 import unittest
 import tempfile