populate fields will not have effect on select fields as supported by Mo...

As far as my understanding, POPULATE fields should have minimum effect on SELECT fields as supported by Mongoose.(from Mongoose Docs)
```
Customer.find()
        .populate('purchased', 'title')
        .exec(function (err, res) {});
```
As supported by Mongoose, Populate will not suppress fields from Customer unless specifically mentioned in select(). The above statement will populate Purchased.title along with other Customer fields.
```
Customer.find()
        .select('dob')
        .populate('purchased', 'title')
        .exec(function (err, res) {});
```
The above statement will populate Purchased.title along with only selected Customer.DOB field.