Fix shorter route helpers in production environment

I don't know exactly when Rails picks each module to use, but this seems to be
used by `app` in the console (for instance, `app.project_path` would fail
before, but works now).

config/application.rb

@@ -166,8 +166,9 @@ module Gitlab
     config.after_initialize do
       Rails.application.reload_routes!
+      named_routes_set = Gitlab::Application.routes.named_routes
       project_url_helpers = Module.new do
-        Gitlab::Application.routes.named_routes.helper_names.each do |name|
+        named_routes_set.helper_names.each do |name|
           next unless name.include?('namespace_project')
           define_method(name.sub('namespace_project', 'project')) do |project, *args|
@@ -176,6 +177,9 @@ module Gitlab
         end
       end
+      named_routes_set.url_helpers_module.include project_url_helpers
+      named_routes_set.url_helpers_module.extend project_url_helpers
+
       Gitlab::Routing.url_helpers.include project_url_helpers
       Gitlab::Routing.url_helpers.extend project_url_helpers