Merge branch 'rails5-fix-utf' into 'master'

Use InvalidUTF8ErrorHandler only for rails 4

Closes #51908

See merge request gitlab-org/gitlab-ce!22340

app/controllers/application_controller.rb

@@ -12,7 +12,9 @@ class ApplicationController < ActionController::Base
   include WorkhorseHelper
   include EnforcesTwoFactorAuthentication
   include WithPerformanceBar
-  include InvalidUTF8ErrorHandler
+  # this can be removed after switching to rails 5
+  # https://gitlab.com/gitlab-org/gitlab-ce/issues/51908
+  include InvalidUTF8ErrorHandler unless Gitlab.rails5?
 
   before_action :authenticate_sessionless_user!
   before_action :authenticate_user!

spec/controllers/application_controller_spec.rb

@@ -685,17 +685,28 @@ describe ApplicationController do
     end
 
     context 'html' do
+      subject { get :index, text: "hi \255" }
+
       it 'renders 412' do
-        get :index, text: "hi \255"
+        if Gitlab.rails5?
+          expect { subject }.to raise_error(ActionController::BadRequest)
+        else
+          subject
 
           expect(response).to have_gitlab_http_status(412)
           expect(response).to render_template :precondition_failed
         end
       end
+    end
 
     context 'js' do
+      subject { get :index, text: "hi \255", format: :js }
+
       it 'renders 412' do
-        get :index, text: "hi \255", format: :js
+        if Gitlab.rails5?
+          expect { subject }.to raise_error(ActionController::BadRequest)
+        else
+          subject
 
           json_response = JSON.parse(response.body)
 
@@ -704,6 +715,7 @@ describe ApplicationController do
         end
       end
     end
+  end
 
   context 'X-GitLab-Custom-Error header' do
     before do