see http://pogma.com/2009/09/09/snow-leopard-and-offlineimap/ and bug 284925

--- a/offlineimap.py	2016-07-31 23:58:39.131404136 +0800
+++ b/offlineimap.py	2016-07-31 23:58:57.987466173 +0800
@@ -20,6 +20,7 @@
 import os
 import sys
 
+from locale import *
 from offlineimap import OfflineImap
 
 oi = OfflineImap()