warn_for_outdated_bundler_version

# File lib/bundler/lockfile_parser.rb, line 102
    def warn_for_outdated_bundler_version
      return unless bundler_version
      prerelease_text = bundler_version.prerelease? ? " --pre" : ""
      current_version = Gem::Version.create(Bundler::VERSION)
      case current_version.segments.first <=> bundler_version.segments.first
      when -1
        raise LockfileError, "You must use Bundler #{bundler_version.segments.first} or greater with this lockfile."
      when 0
        if current_version < bundler_version
          Bundler.ui.warn "Warning: the running version of Bundler (#{current_version}) is older "                 "than the version that created the lockfile (#{bundler_version}). We suggest you "                 "upgrade to the latest version of Bundler by running `gem "                 "install bundler#{prerelease_text}`.\n"
        end
      end
    end