Clear html cache for a projects milestones

lib/gitlab/database/rename_reserved_paths_migration/v1/rename_base.rb

@@ -107,6 +107,10 @@ module Gitlab
             update_column_in_batches(:notes, :note_html, nil) do |table, query|
               query.where(table[:project_id].in(project_ids))
             end
+
+            update_column_in_batches(:milestones, :description_html, nil) do |table, query|
+              query.where(table[:project_id].in(project_ids))
+            end
           end
 
           def file_storage?

spec/lib/gitlab/database/rename_reserved_paths_migration/v1/rename_base_spec.rb

@@ -65,6 +65,16 @@ describe Gitlab::Database::RenameReservedPathsMigration::V1::RenameBase do
 
       expect(note.reload.note_html).to be_nil
     end
+
+    it 'removes milestone description' do
+      milestone = create(:milestone,
+                    project: project,
+                    description_html: 'milestone description')
+
+      subject.remove_cached_html_for_projects([project.id])
+
+      expect(milestone.reload.description_html).to be_nil
+    end
   end
 
   describe '#rename_path_for_routable' do