Gemfile in signed_form-0.0.1.pre1 vs Gemfile in signed_form-0.0.1

@@ -1,4 +1,20 @@
 source 'https://rubygems.org'
 
 # Specify your gem's dependencies in signed_form.gemspec
 gemspec
+
+rails_version = ENV['RAILS_VERSION'] || 'master'
+
+case rails_version
+when /master/
+  gem "rails", github: "rails/rails"
+when /3-2-stable/
+  gem "rails", github: "rails/rails", branch: "3-2-stable"
+when /3-1-stable/
+  gem "rails", github: "rails/rails", branch: "3-1-stable"
+when /3-0-stable/
+  gem "rails", github: "rails/rails", branch: "3-0-stable"
+else
+  gem "rails", ENV['RAILS_VERSION']
+end
+