class Gem::Tasks::SCM::Tag

def define
  task :validate
  namespace :scm do
    task :tag, [:name] => :validate do |t,args|
      tag = (args.name || version_tag(@project.gemspec.version))
      status "Tagging #{tag} ..."
      unless tag!(tag)
        error "Could not create tag #{tag}"
      end
    end
  end
end