Link to milestone in "Milestone changed" system note

app/services/system_note_service.rb

@@ -41,7 +41,7 @@ class SystemNoteService
   #
   # Returns the created Note object
   def self.change_assignee(noteable, project, author, assignee)
-    body = assignee.nil? ? 'Assignee removed' : "Reassigned to @#{assignee.username}"
+    body = assignee.nil? ? 'Assignee removed' : "Reassigned to #{assignee.to_reference}"
 
     create_note(noteable: noteable, project: project, author: author, note: body)
   end
@@ -103,7 +103,7 @@ class SystemNoteService
   # Returns the created Note object
   def self.change_milestone(noteable, project, author, milestone)
     body = 'Milestone '
-    body += milestone.nil? ? 'removed' : "changed to #{milestone.title}"
+    body += milestone.nil? ? 'removed' : "changed to #{milestone.to_reference(project)}"
 
     create_note(noteable: noteable, project: project, author: author, note: body)
   end

app/views/shared/issuable/_sidebar.html.haml

@@ -28,8 +28,7 @@
           %span.back-to-milestone
             = link_to namespace_project_milestone_path(@project.namespace, @project, issuable.milestone) do
               %strong
-                = icon('clock-o')
-                = issuable.milestone.title
+                = issuable.milestone.reference_link_text
         - else
           .light None
       .selectbox

spec/services/system_note_service_spec.rb

@@ -171,7 +171,7 @@ describe SystemNoteService, services: true do
 
     context 'when milestone added' do
       it 'sets the note text' do
-        expect(subject.note).to eq "Milestone changed to #{milestone.title}"
+        expect(subject.note).to eq "Milestone changed to #{milestone.to_reference}"
       end
     end