Gemfile in statesman-4.1.1 vs Gemfile in statesman-4.1.2

@@ -1,9 +1,15 @@
 source 'https://rubygems.org'
 
 gemspec
 
-gem "rails", "~> #{ENV['RAILS_VERSION']}" if ENV["RAILS_VERSION"]
+# rubocop:disable Bundler/DuplicatedGem
+if ENV['RAILS_VERSION'] == 'master'
+  gem "rails", git: "https://github.com/rails/rails"
+elsif ENV['RAILS_VERSION']
+  gem "rails", "~> #{ENV['RAILS_VERSION']}"
+end
+# rubocop:enable Bundler/DuplicatedGem
 
 group :development do
   gem "mongoid", ">= 3.1" unless ENV["EXCLUDE_MONGOID"]
 
   # test/unit is no longer bundled with Ruby 2.2, but required by Rails