--- a/plugins/mod_admin_telnet.lua	Sat Jul 09 00:56:32 2016 +0800
+++ b/plugins/mod_admin_telnet.lua	Sat Jul 09 00:57:17 2016 +0800
@@ -732,7 +732,6 @@
 end
 
 function def_env.s2s:showcert(domain)
-	local ser = require "util.serialization".serialize;
 	local print = self.session.print;
 	local s2s_sessions = module:shared"/*/s2s/sessions";
 	local domain_sessions = set.new(array.collect(values(s2s_sessions)))