[5.4] Some refactoring on Eloquent builder

[themsaid]

Extracted a new method that'll create a new model instance and set the connection to the same connection of the Builder instance:

public function newModelInstance($attributes = [])
{
    return $this->model->newInstance($attributes)->setConnection(
        $this->query->getConnection()->getName()
    );
}

Refactored the areas where this logic used to happen to call the method instead.

• some minor docblock fixes.

[taylorotwell]

Thanks

[gabrielkoerich]

@themsaid This commit introduced a bug in my tests, if I create a model just using new Model() and save(), the connection is null, so all my comparisons using $model->is(...) doens't work anymore. Maybe we should use this new method in save() too? I don't know.

[themsaid]

@gabrielkoerich I don't think this commit made a change to the code, we just extracted part of the code in a method.

[gabrielkoerich]

@themsaid Yeap, that's weird. It was something between 5.4.18 and 5.4.19 (v5.4.18...v5.4.19), and the only commit that changed something with connections was this one... Do you know what else could it be? Thanks.

[gabrielkoerich]

@themsaid I end up calling fresh() after creating the model and it's working.