NameError: undefined local variable or method `define_tree_vars' for #<Projects::RefsController:0x007f1eca87...

Created by @rymai.

https://sentry.gitlap.com/gitlab/gitlabcom/issues/18569/

NameError: undefined local variable or method `define_tree_vars' for #<Projects::RefsController:0x007f1eca87c928>
Did you mean?  define_singleton_method
  app/controllers/projects/application_controller.rb:66:in `method_missing'
    super
  app/controllers/projects/refs_controller.rb:38:in `block (2 levels) in switch'
    define_tree_vars
  app/controllers/projects/refs_controller.rb:12:in `switch'
    respond_to do |format|
  lib/gitlab/middleware/multipart.rb:93:in `call'
    return @app.call(env) if encoded_message.blank?
  lib/gitlab/request_profiler/middleware.rb:15:in `call'
    @app.call(env)
...
(113 additional frame(s) were not displayed)

NameError: undefined local variable or method `define_tree_vars' for #<Projects::RefsController:0x007f1eca87c928>
Did you mean?  define_singleton_method

It seems that #define_tree_vars was removed but I cannot find when...