ActiveRecord :include doesn't work with foreign keys

When creating a belongs_to association in an ActiveRecord model it's possible to have the model eager load the associated model. For example:

class Student < ActiveRecord::Base

belongs_to :lecturer

end

Using: Student.find(:all, :include => :lecturer) - should bring all the students and their lecturers, resulting in a query like "SELECT * from lecturers WHERE id IN (1, 2, 3)".

However, if we use a foreign key like so:

class Student < ActiveRecord::Base

belongs_to :lecturer, :foreign_key => :some_key

end

Using the above find will eager load only the lecturer for the first student. The rest will be lazy loaded.