This error is raised if HTTP authentication is required, but not provided.
# File bundler/fetcher.rb, line 43
def initialize(remote_uri)
remote_uri = filter_uri(remote_uri)
super "Authentication is required for #{remote_uri}.\n" \
"Please supply credentials for this source. You can do this by running:\n" \
" bundle config #{remote_uri} username:password"
end