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_tup = highest_remote_name_tuple l_spec
    highest_remote_ver = highest_remote_tup.version
    highest_installed_ver = l_spec.version
    if system or (highest_installed_ver < highest_remote_ver)
      result << Gem::NameTuple.new(l_spec.name, [highest_installed_ver, highest_remote_ver].max, highest_remote_tup.platform)
    end
  end
  result
end