class Rails::Generators::PluginGenerator

def rails_gemfile_entry
  if options[:skip_gemspec]
    super
  elsif rails_prerelease?
    super.dup.tap do |entry|
      entry.comment = <<~COMMENT
        Your gem is dependent on a prerelease version of Rails. Once you can lock this
        dependency down to a specific version, move it to your gemspec.
      COMMENT
    end
  end
end