I think this was caused when we upgraded Circle CI machines a few weeks ago (though I'm not sure why it only started failing today). The issue was we were installing a specific version of Bundler to get around a bug with Bundler. Since we're on a new enough version by default on the CI machines, I took out the explicit installation step (which was failing while waiting for user input to confirm replacing the already-installed version).
Matches the change made here: https://github.com/artsy/emission/commit/5187b967414872b82fd525c1a51503172c967d1e
I think this was caused when we upgraded Circle CI machines a few weeks ago (though I'm not sure why it only started failing today). The issue was we were installing a specific version of Bundler to get around a bug with Bundler. Since we're on a new enough version by default on the CI machines, I took out the explicit installation step (which was failing while waiting for user input to confirm replacing the already-installed version).