fix moosefs.ReadableFile has no next()
fix moosefs.ReadableFile has no next()

Mignet/dpark,quxiaolong1504/dpark,Mignet/dpark,ee08b397/dpark,mageia/dpark,douban/dpark,fe11x/dpark,fe11x/dpark,smarthomekit/dpark,douban/dpark,oceanjack/dpark,veritynoob/dpark,smarthomekit/dpark,mageia/dpark,smarthomekit/dpark,yhj630520/dpark,304471720/dpark,douban/dpark,304471720/dpark,junmoa/dpark,304471720/dpark,windreamer/dpark,dogeyes/dpark,zzl0/dpark,veritynoob/dpark,douban/dpark,dogeyes/dpark,zzl0/dpark,yhj630520/dpark,veritynoob/dpark,daishaowei/dpark,yhj630520/dpark,oceanjack/dpark,yanheven/dpark,windreamer/dpark,windreamer/dpark,windreamer/dpark,quxiaolong1504/dpark,junmoa/dpark,dogeyes/dpark,daishaowei/dpark,douban/dpark,yanheven/dpark