Bundler 1.1 has been released. With this version you no longer need to wait for this:

Fetching source index…

Rails Long Term Support

Rails LTS provides security patches for old versions of Ruby on Rails (2.3, 3.2, 4.2 and 5.2)

• Prevents you from data breaches and liability risks
• Upgrade at your own pace
• Works with modern Rubies

Read more Show archive.org snapshot

The new Bundler is smarter Show archive.org snapshot and can fetch required metadata in a few seconds.

You can install the new version by saying:

sudo gem install bundler