Don't use set() since it's not in python 2.3.

Just use a plain list instead.  Technically probably slightly worse
asymptotic behaviour, but it's not like we'll have a million sockets anyway.

helpers.py

@@ -28,3 +28,10 @@ def debug3(s):
 
 class Fatal(Exception):
     pass
+
+
+def list_contains_any(l, sub):
+    for i in sub:
+        if i in l:
+            return True
+    return False