По привычке набрал команду
bundle
и получил лапидарное сообщение:
Could not verify the SSL certificate for https://rubygems.org/.
There is a chance you are experiencing a man-in-the-middle attack, but most likely your system doesn’t have the CA certificates needed for verification. For information about OpenSSL certificates, see bit.ly/ruby-ssl. To connect without using SSL, edit your Gemfile sources and change ‘https’ to ‘http’.
Вылечилось командой:
rvm osx-ssl-certs update
