concern create duplicate routes for nested resources

[ryanhertz]

If the concern is used on a nested resource, duplicate routes are generated.

    concern :foo do
      get 'bar'
    end

    resources :one do
      resources :two, concerns: :foo
    end

The above produces this:

one_two_bar GET  (/:portal_slug)/one/:one_id/two/:two_id/bar(.:format)  two#bar {:concerns=>:foo}
            GET  (/:portal_slug)/one/:one_id/two/:two_id/bar(.:format)  two#bar {:concerns=>:foo}