class Bundler::Bundle

def list_outdated(options={})
  outdated_gems = source_index.outdated.sort
  if outdated_gems.empty?
    Bundler.logger.info "All gems are up to date."
  else
    Bundler.logger.info "Outdated gems:"
    outdated_gems.each do |name|
      Bundler.logger.info " * #{name}"
    end
  end
end