Error installing under Rails 3.1rc

[yadoga]

Attempted to install with Rails 3.1rc using Ruby 1.9.2

rails plugin install git://github.com/fidel/batch_translations.git

results in

Volumes/mydisc/Users/myname/.rvm/gems/ruby-1.9.2-p180@rails31beta/gems/railties-3.1.0.rc1/lib/rails/commands/plugin.rb:277:in '<top (required)>': Commands is not a module (TypeError) from /Volumes/mydisc/Users/myname/.rvm/gems/ruby-1.9.2-p180@rails31beta/gems/activesupport-3.1.0.rc1/lib/active_support/dependencies.rb:237:in `require' (and so forth…)