FIX: wrong category links on subfolder install in rss feed for a category topic list

app/controllers/list_controller.rb

@@ -219,8 +219,8 @@ class ListController < ApplicationController
     discourse_expires_in 1.minute
 
     @title = "#{@category.name} - #{SiteSetting.title}"
-    @link = "#{Discourse.base_url}#{@category.url}"
-    @atom_link = "#{Discourse.base_url}#{@category.url}.rss"
+    @link = "#{Discourse.base_url_no_prefix}#{@category.url}"
+    @atom_link = "#{Discourse.base_url_no_prefix}#{@category.url}.rss"
     @description = "#{I18n.t('topics_in_category', category: @category.name)} #{@category.description}"
     @topic_list = TopicQuery.new(current_user).list_new_in_category(@category)
 

spec/requests/list_controller_spec.rb

@@ -393,6 +393,15 @@ RSpec.describe ListController do
           expect(response.status).to eq(200)
           expect(response.content_type).to eq('application/rss+xml')
         end
+
+        it "renders RSS in subfolder correctly" do
+          GlobalSetting.stubs(:relative_url_root).returns('/forum')
+          Discourse.stubs(:base_uri).returns("/forum")
+          get "/c/#{category.slug}.rss"
+          expect(response.status).to eq(200)
+          expect(response.body).to_not include("/forum/forum")
+          expect(response.body).to include("http://test.localhost/forum/c/#{category.slug}")
+        end
       end
 
       describe "category default views" do