Gem::Commands::UpdateCommand#rubygems_target_version

# File tmp/rubies/ruby-4.1.0-preview1/lib/rubygems/commands/update_command.rb, line 295
def rubygems_target_version
  version = options[:system]
  update_latest = version == true

  unless update_latest
    version     = Gem::Version.new     version
    requirement = Gem::Requirement.new version

    return version, requirement
  end

  version     = Gem::Version.new     Gem::VERSION
  requirement = Gem::Requirement.new ">= #{Gem::VERSION}"

  rubygems_update         = Gem::Specification.new
  rubygems_update.name    = "rubygems-update"
  rubygems_update.version = version

  highest_remote_tup = highest_remote_name_tuple(rubygems_update)
  target = highest_remote_tup ? highest_remote_tup.version : version

  [target, requirement]
end