Gem::Commands::UpdateCommand#update_rubygems

# File tmp/rubies/ruby-4.0.0/lib/rubygems/commands/update_command.rb, line 269
def update_rubygems
  if Gem.disable_system_update_message
    alert_error Gem.disable_system_update_message
    terminate_interaction 1
  end

  check_update_arguments

  version, requirement = rubygems_target_version

  check_latest_rubygems version

  check_oldest_rubygems version

  installed_gems = Gem::Specification.find_all_by_name "rubygems-update", requirement
  installed_gems = update_gem("rubygems-update", requirement) if installed_gems.empty? || installed_gems.first.version != version
  return if installed_gems.empty?

  install_rubygems installed_gems.first
end