safeguard more than 1 reply panic

wechatMsg.go

@@ -29,7 +29,8 @@ func (m *InWechatMsg) replyXML(xml string) {
 		m.replied = true
 		m.instantResponse <- xml
 	} else {
-		log.Println("BUG::doubl reply for wechat message")
+		d := decryptToXML(xml)
+		log.Println("BUG::double reply for wechat message\n" + d + "\n")
 	}
 }