Allows html in commits atom feed

Html code now works in commits atom feed `title` and `summary`.

app/views/projects/commits/_commit.atom.builder

 xml.entry do
   xml.id      project_commit_url(@project, id: commit.id)
   xml.link    href: project_commit_url(@project, id: commit.id)
-  xml.title   truncate(commit.title, length: 80)
+  xml.title   truncate(commit.title, length: 80, escape: false)
   xml.updated commit.committed_date.xmlschema
   xml.media   :thumbnail, width: "40", height: "40", url: image_url(avatar_icon(commit.author_email))
 
@@ -10,5 +10,5 @@ xml.entry do
     xml.email commit.author_email
   end
 
-  xml.summary markdown(commit.description, pipeline: :single_line)
+  xml.summary markdown(commit.description, pipeline: :single_line), type: 'html'
 end

changelogs/unreleased/41208-commit-atom-feeds-double-escaped.yml

+---
+title: Allows html text in commits atom feed
+merge_request: 16603
+author: Jacopo Beschi @jacopo-beschi
+type: fixed

spec/controllers/projects/commits_controller_spec.rb

@@ -41,15 +41,21 @@ describe Projects::CommitsController do
 
     context "when the ref name ends in .atom" do
       context "when the ref does not exist with the suffix" do
-        it "renders as atom" do
+        before do
           get(:show,
               namespace_id: project.namespace,
               project_id: project,
               id: "master.atom")
+        end
 
+        it "renders as atom" do
           expect(response).to be_success
           expect(response.content_type).to eq('application/atom+xml')
         end
+
+        it 'renders summary with type=html' do
+          expect(response.body).to include('<summary type="html">')
+        end
       end
 
       context "when the ref exists with the suffix" do