Fix uninstall of newer bundler for old rails

Author: JonRowe

script/downgrade_bundler_on_old_rails

@@ -12,7 +12,7 @@ if ruby -e "exit(ENV['RAILS_VERSION'].scan(/\d+\.\d+.\d+/)[0].to_f < 5)"; then
   gem uninstall -aIx bundler || echo "Warning error occured removing bundler via gem"
 
   # this only works on Ruby 2.3 which is luckily the version we need to fix
-  if is_ruby_23; then
+  if ruby -e "exit(RUBY_VERSION.to_f == 2.3)"; then
     rvm @global do gem uninstall -aIx bundler
   fi