Rails 4.2 implements #model_name in ActiveRecord::Base as an instance method rather than a class method (in 4.1 and older), changed in https://github.com/rails/rails/commit/6b0e834.

Our HasManyCommon concern adds a model_name method to Host::Base as an extension of the model/model_id association to the Model er, model. This will need to be removed to ensure the AR method continues to work.

When our model is in place, links to hosts can't be generated in Rails 4.2 as they return nil or string values from our implementation Host::Base#model_name rather than the ActiveModel::Name object expected.