def rvm_task(name,&block)
      if fetch(:rvm_require_role,nil).nil?
        task name, &block
      else
        task name, :roles => fetch(:rvm_require_role), &block
      end
    end
def rvm_task(name,&block)
      if fetch(:rvm_require_role,nil).nil?
        task name, &block
      else
        task name, :roles => fetch(:rvm_require_role), &block
      end
    end
defined depending on which selector was used