laravel/framework — pull request #811 by raftalks (2013-04-02 23:25:29+00:00)
Title: Mass Assigning Polymorph relation on create

I have noticed that when using create method on Polymorph model instance the attribute array passed to method needs to go through
mass assigning if fillable attribute is defined in the model, and needs to set the foreign key and morph type. This fixed the issue of not been able to mass assign a polymorph model on creation.