Model.hydrate doesn't select projections

[RayofLightz]

When passing a projections object to Model.hydrate it does not actually select the fields from the projection like the documentation states.
According to the hydration docs
projection fields "should be selected for this document".

const mongoose = require('mongoose');
const PieSchema = new mongoose.Schema({ filling : String, hoursToMake : Number, tasteRating : Number });
const Pie = mongoose.model('Pie', PieSchema);
console.log(Pie.hydrate({ filling : 'cherry', hoursToMake : 2 }, { filling : 1 }));
// Outputs { filling : 'cherry', hoursToMake : 2 }

It should be returning { filling : 'cherry' }

I am on 14.18.3 of node, 5.13.2 of mongoose, and 4.4.6 of mongo