Installing the Bundler gem?

Question

ruby gems

When trying to install the gem, Bundler gives the following error:

>jruby -S gem install bundler
NameError: missing class name (`org.jruby.ext.psych.PsychLibrary')
  get_proxy_or_package_under_package at org/jruby/javasupport/JavaUtilities.java:54
                      method_missing at uri:classloader:/jruby/java/java_package_module_template.rb:14
                               <top> at D:/Dev/!Trans/jruby-9.0.1.0/lib/ruby/stdlib/psych.rb:4
                             require at org/jruby/RubyKernel.java:939
                              (root) at D:/Dev/!Trans/jruby-9.0.1.0/lib/ruby/stdlib/rubygems/core_ext/kernel_require.rb:1
                             require at D:/Dev/!Trans/jruby-9.0.1.0/lib/ruby/stdlib/rubygems/core_ext/kernel_require.rb:54
                           load_yaml at D:/Dev/!Trans/jruby-9.0.1.0/lib/ruby/stdlib/rubygems.rb:609
                           load_file at D:/Dev/!Trans/jruby-9.0.1.0/lib/ruby/stdlib/rubygems/config_file.rb:328
                          initialize at D:/Dev/!Trans/jruby-9.0.1.0/lib/ruby/stdlib/rubygems/config_file.rb:197
                    do_configuration at D:/Dev/!Trans/jruby-9.0.1.0/lib/ruby/stdlib/rubygems/gem_runner.rb:74
                               <top> at D:/Dev/!Trans/jruby-9.0.1.0/lib/ruby/stdlib/rubygems/gem_runner.rb:39
                                load at org/jruby/RubyKernel.java:957
                               <top> at D:/Dev/!Trans/jruby-9.0.1.0/bin/gem:4

I perform the installation to work with Heroku, I do everything according to this instruction. Tried both JRuby 9.0.0.0 and 9.0.1.0, same error.
Win7 x64 prof system, JDK 1.8.