class Bundler::RubygemsIntegration::Future

def download_gem(spec, uri, path)
  uri = Bundler.settings.mirror_for(uri)
  fetcher = gem_remote_fetcher
  fetcher.headers = { "X-Gemfile-Source" => spec.remote.original_uri.to_s } if spec.remote.original_uri
  Bundler::Retry.new("download gem from #{uri}").attempts do
    fetcher.download(spec, uri, path)
  end
end