target_rails_prerelease

# File railties/lib/rails/generators/app_base.rb, line 421
      def target_rails_prerelease(self_command = "new")
        return unless rails_prerelease? && bundle_install?

        if !File.exist?(File.expand_path("Gemfile", destination_root))
          create_file("Gemfile", <<~GEMFILE)
            source "https://rubygems.org"
            git_source(:github) { |repo| "https://github.com/\#{repo}.git" }
            #{rails_gemfile_entry}
          GEMFILE

          run_bundle

          @argv[0] = destination_root
          require "shellwords"
          bundle_command("exec rails #{self_command} #{Shellwords.join(@argv)}")
          exit
        else
          remove_file("Gemfile")
          remove_file("Gemfile.lock")
        end
      end