Capping rails version since 3.2.14 doesn't work

When running our code with Rails 3.2.14, we get errors such as the one below.
We're doing Provider.joins(:provider) which I'm guessing no longer works with
Rails.

    ActiveRecord::ConfigurationError:
       Association named 'provider' was not found on Provider; perhaps you misspelled it?
     # ./app/models/authorization/product.rb:22:in `block (2 levels) in
     # <module:Product>'
     # ./app/models/authorization/repository.rb:43:in `content_readable'
     # ./app/models/authorization/repository.rb:36:in
     # `libraries_content_readable'
     # ./app/controllers/content_search_controller.rb:577:in `process_repos'
     # ./app/controllers/content_search_controller.rb:100:in `packages'
     # ./app/lib/util/thread_session.rb:104:in `thread_locals'
     # ./spec/controllers/content_search_controller_spec.rb:81:in `block (6
     # levels) in <top (required)>'