Fix to allow setting a `requester` on recursive calls to `request.defaults`

Right now in `request.defaults` in checks if the `method === request` to know if it should use the passed in `requester`

The issue is that on recursive calls to `request.defaults` the `method` will not `===` to `request`, it will be the function returned from `request.defaults`.

This PR changes the check to use `method === self` instead so that you can set a `requester` on recursive calls to`request.defaults`