Fix spec for Rails 5

spec/controllers/uploads_controller_spec.rb

@@ -8,7 +8,11 @@ end
 shared_examples 'content not cached without revalidation and no-store' do
   it 'ensures content will not be cached without revalidation' do
     # Fixed in newer versions of ActivePack, it will only output a single `private`.
-    expect(subject['Cache-Control']).to eq('max-age=0, private, must-revalidate, private, no-store')
+    if Gitlab.rails5?
+      expect(subject['Cache-Control']).to eq('max-age=0, private, must-revalidate, no-store')
+    else
+      expect(subject['Cache-Control']).to eq('max-age=0, private, must-revalidate, private, no-store')
+    end
   end
 end