fix_Gemfile.lock

#!/bin/bash

sentinel='if RbConfig'
sed -i '.bak' -e "s/^${sentinel}.*$/if false/" Gemfile
bundle
git update-index --no-assume-unchanged Gemfile.lock
git add Gemfile.lock
mv Gemfile.bak Gemfile
bundle
git co Gemfile.lock
git update-index --assume-unchanged Gemfile.lock

Gemfile

source :rubygems

gem 'rails'

# Or find something else that returns true
# locally, but false on heroku
if RbConfig::CONFIG['host_os'] =~ /darwin/
  group :test do
    # heroku fails hard on this gem
    gem 'specjour'
  end
end