Ruby, gem and Bundler

When bundler cannot find a gem

A gem nobody approved yet looks like it does not exist.

Bundler reads the version list of every gem it might need, old versions included. A gem nobody approved yet shows no versions, so Bundler says it cannot find it:

$ bundle install
Fetching gem metadata from https://packages.example.com/rubygems/.
Could not find gem 'colorize' in rubygems repository https://rubygems.org/ or
installed locally.

Captured by running these commands against a real ForgeRepo™.

Ask for the gem on the Requests page. A download of a gem that is not approved is refused with a 451 status, and Bundler prints the reason.