should fix error:

TypeError: Cannot read property 'type' of undefined
    at Client.determine_reply_handler (/home/shunanya/worksp_node/test/node_modules/memcache/lib/memcache.js:260:30)
    at Client.handle_received_data (/home/shunanya/worksp_node/test/node_modules/memcache/lib/memcache.js:217:21)
    at Socket.Client.connect.conn.addListener.self.conn (/home/shunanya/worksp_node/test/node_modules/memcache/lib/memcache.js:62:12)
    at Socket.EventEmitter.emit (events.js:88:17)
    at TCP.onread (net.js:403:14)