LearnBoost/mongoose — pull request #1492 by pgherveou (2013-05-18 21:29:31+00:00)
Title: documentArray#id

Hi Aaron, I have this scnerio where I popuate the _id key of a document
and this prevent the documentarray id method to work, this pull request solve that
let me know what you think.

Here is the detailed scenario
```js

GameSchema = new Schema({
players: [PlayerSchema]
// other paths...
})

PlayerSchema = new Schema(
{_id: {type: ObjectId, ref: 'User'}}
// other paths...
}

Game
.findById(gameId)
.populate('players._id')
.exec(function(err, game) {
// game.players.id fails to find anything now
// because we populated players._id path
// and game.players._id is a populated Document
console.log game.players.id(playerId);
})
```