Postponing the Bundler merge.

I faced a big issue about Bundler with ruby core.
  I have no time to resolve it issue before 2.5 final release.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@61416 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

lib/bundler/vendored_persistent.rb

@@ -1,52 +0,0 @@
-# frozen_string_literal: true
-
-# We forcibly require OpenSSL, because net/http/persistent will only autoload
-# it. On some Rubies, autoload fails but explicit require succeeds.
-begin
-  require "openssl"
-rescue LoadError
-  # some Ruby builds don't have OpenSSL
-end
-module Bundler
-  module Persistent
-    module Net
-      module HTTP
-      end
-    end
-  end
-end
-require "bundler/vendor/net-http-persistent/lib/net/http/persistent"
-
-module Bundler
-  class PersistentHTTP < Persistent::Net::HTTP::Persistent
-    def connection_for(uri)
-      connection = super
-      warn_old_tls_version_rubygems_connection(uri, connection)
-      connection
-    end
-
-    def warn_old_tls_version_rubygems_connection(uri, connection)
-      return unless connection.use_ssl?
-      return unless (uri.host || "").end_with?("rubygems.org")
-
-      socket = connection.instance_variable_get(:@socket)
-      return unless socket
-      socket_io = socket.io
-      return unless socket_io.respond_to?(:ssl_version)
-      ssl_version = socket_io.ssl_version
-
-      case ssl_version
-      when /TLSv([\d\.]+)/
-        version = Gem::Version.new($1)
-        if version < Gem::Version.new("1.2")
-          Bundler.ui.warn \
-            "Warning: Your Ruby version is compiled against a copy of OpenSSL that is very old. " \
-            "Starting in January 2018, RubyGems.org will refuse connection requests from these " \
-            "very old versions of OpenSSL. If you will need to continue installing gems after " \
-            "January 2018, please follow this guide to upgrade: http://ruby.to/tls-outdated.",
-            :wrap => true
-        end
-      end
-    end
-  end
-end