class Bundler::Fetcher::CompactIndex

def available?
  user_home = Pathname.new(Bundler.rubygems.user_home)
  return nil unless user_home.directory? && user_home.writable?
  # Read info file checksums out of /versions, so we can know if gems are up to date
  fetch_uri.scheme != "file" && compact_index_client.update_and_parse_checksums!
rescue CompactIndexClient::Updater::MisMatchedChecksumError => e
  Bundler.ui.warn(e.message)
  nil
end