Project#show on projects pending deletion will 404

fixes #17508

CHANGELOG

@@ -11,6 +11,7 @@ v 8.9.0 (unreleased)
   - Fix issues filter when ordering by milestone
   - Todos will display target state if issuable target is 'Closed' or 'Merged'
   - Remove 'main language' feature
+  - Projects pending deletion will render a 404 page
   - Measure queue duration between gitlab-workhorse and Rails
 
 v 8.8.3

app/controllers/projects/application_controller.rb

@@ -26,7 +26,7 @@ class Projects::ApplicationController < ApplicationController
       project_path = "#{namespace}/#{id}"
       @project = Project.find_with_namespace(project_path)
 
-      if @project && can?(current_user, :read_project, @project)
+      if can?(current_user, :read_project, @project) && !@project.pending_delete?
         if @project.path_with_namespace != project_path
           redirect_to request.original_url.gsub(project_path, @project.path_with_namespace)
         end

spec/controllers/projects_controller_spec.rb

@@ -115,6 +115,17 @@ describe ProjectsController do
         expect(public_project_with_dot_atom).not_to be_valid
       end
     end
+
+    context 'when the project is pending deletions' do
+      it 'renders a 404 error' do
+        project = create(:project, pending_delete: true)
+        sign_in(user)
+
+        get :show, namespace_id: project.namespace.path, id: project.path
+
+        expect(response.status).to eq 404
+      end
+    end
   end
 
   describe "#update" do