Fix transient refleaks in test_urllib. Thanks to Florent Xicluna.
diff --git a/Lib/urllib.py b/Lib/urllib.py
index 1c31d48..be77e1d 100644
--- a/Lib/urllib.py
+++ b/Lib/urllib.py
@@ -95,6 +95,8 @@
 def urlcleanup():
     if _urlopener:
         _urlopener.cleanup()
+    _safemaps.clear()
+    ftpcache.clear()
 
 # check for SSL
 try: