Git errors during a bundle install

When your tests run, during the bundle install step, you might see something like this:

Git error: command `git clone '' "/home/ubuntu/circle-2/vendor/bundle/ruby/1.9.1/cache/bundler/git/rails-47ba0391b239cf6d20fc732cd925192bcf3430fc" --bare --no-hardlinks` in directory /home/ubuntu/circle-1 has failed.
Permission denied (publickey).
fatal: The remote end hung up unexpectedly

This happens because you have a git repository listed as a dependency in your Gemfile:

gem "rails", :git => "git://"

If the repository is public, just change the dependency to use a https url:

gem "rails", :git => ""

If the repository is private, you will need to enable user keys from your project’s Project Settings > Checkout SSH keys page.