Revert "Remove libexec/bundle_ruby"

This reverts commit 3f708604920f2fd7a105d5f092240737add15ef1.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@66220 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

libexec/bundle_ruby

@@ -0,0 +1,60 @@
+#!/usr/bin/env ruby
+# frozen_string_literal: true
+
+require "bundler/shared_helpers"
+
+Bundler::SharedHelpers.major_deprecation(3, "the bundle_ruby executable has been removed in favor of `bundle platform --ruby`")
+
+Signal.trap("INT") { exit 1 }
+
+require "bundler/errors"
+require "bundler/ruby_version"
+require "bundler/ruby_dsl"
+
+module Bundler
+  class Dsl
+    include RubyDsl
+
+    attr_accessor :ruby_version
+
+    def initialize
+      @ruby_version = nil
+    end
+
+    def eval_gemfile(gemfile, contents = nil)
+      contents ||= File.open(gemfile, "rb", &:read)
+      instance_eval(contents, gemfile.to_s, 1)
+    rescue SyntaxError => e
+      bt = e.message.split("\n")[1..-1]
+      raise GemfileError, ["Gemfile syntax error:", *bt].join("\n")
+    rescue ScriptError, RegexpError, NameError, ArgumentError => e
+      e.backtrace[0] = "#{e.backtrace[0]}: #{e.message} (#{e.class})"
+      STDERR.puts e.backtrace.join("\n       ")
+      raise GemfileError, "There was an error in your Gemfile," \
+        " and Bundler cannot continue."
+    end
+
+    def source(source, options = {})
+    end
+
+    def gem(name, *args)
+    end
+
+    def group(*args)
+    end
+  end
+end
+
+dsl = Bundler::Dsl.new
+begin
+  dsl.eval_gemfile(Bundler::SharedHelpers.default_gemfile)
+  ruby_version = dsl.ruby_version
+  if ruby_version
+    puts ruby_version
+  else
+    puts "No ruby version specified"
+  end
+rescue Bundler::GemfileError => e
+  puts e.message
+  exit(-1)
+end