fixed error no such item for Cursor instance

an error occured when run `scrapy crawl member`.
error message: `no such item for Cursor instance`

os version: centos 6.2
mongo db version v2.6.4
python version: 2.7.6
pymongo version:2.7.2

problem resoved 
url:http://stackoverflow.com/questions/12060402/using-pymongos-replicasetconnection-sometimes-getting-indexerror-no-such-ite