Fix a bug in the replay_iterator
Fix a bug in the replay_iterator

Entries added during iteration could be overwritten and lost.

influxdb/HyperLevelDB,influxdb/HyperLevelDB,tempbottle/HyperLevelDB,yonglehou/HyperLevelDB,rescrv/HyperLevelDB,dyu-deploy/HyperLevelDB,yonglehou/HyperLevelDB,tempbottle/HyperLevelDB,rescrv/HyperLevelDB,norton/HyperLevelDB,norton/HyperLevelDB,dyu-deploy/HyperLevelDB