I have bundler 1.11.2 locally, which adds the `!`'s. On the server bundler is 1.10.6 and `bundle install` fails with:
Warning: the running version of Bundler is older than the version that created the lockfile. We suggest you upgrade to the latest version of Bundler by running `gem install bundler`.
You are trying to install in deployment mode after changing your Gemfile. Run `bundle install` elsewhere and add the updated Gemfile.lock to version control.
If this is a development machine, remove the Gemfile freeze by running `bundle install --no-deployment`.
If I revert the commit which adds the `!`'s `bundle install` on the server works again. I'd imagine that the client/server versions didn't have to be exactly the same, just the same major version.