Workaround for n+1 in Projects::TreeController#show

See https://gitlab.com/gitlab-org/gitlab-ce/issues/38261

app/controllers/projects/tree_controller.rb

@@ -35,10 +35,13 @@ class Projects::TreeController < Projects::ApplicationController
       end
 
       format.json do
+        # n+1: https://gitlab.com/gitlab-org/gitlab-ce/issues/38261
+        Gitlab::GitalyClient.allow_n_plus_1_calls do
           render json: TreeSerializer.new(project: @project, repository: @repository, ref: @ref).represent(@tree)
         end
       end
     end
+  end
 
   def create_dir
     return render_404 unless @commit_params.values.all?