You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: deprecated_assignee.rb
    path of file: ./repos/gitlabhq/app/models/concerns
    
    the code of the file until where you have to start completion: # frozen_string_literal: true

# This module handles backward compatibility for import/exp
    
  def update_assignees_relation
    if pending_assignees_population?
      transaction do
        merge_request_assignees.create!(user_id: deprecated_assignee_id, merge_request_id: id)
        update_column(:assignee_id, nil)
      end
    end