class Gem::Commands::UpdateCommand

def which_to_update highest_installed_gems, gem_names, system = false
  result = []
  highest_installed_gems.each do |l_name, l_spec|
    next if not gem_names.empty? and
            gem_names.none? { |name| name == l_spec.name }
    highest_remote_ver = highest_remote_version l_spec
    if system or (l_spec.version < highest_remote_ver) then
      result << [l_spec.name, [l_spec.version, highest_remote_ver].max]
    end
  end
  result
end