Jruby: unable to install gems, failing with undefined class/module YAML::Syck::DefaultKey

The console output pretty much speaks for itself:

$ java -jar jruby-complete-1.6.4.jar -S gem install nokogiri --no-rdoc --no-ri
Fetching: nokogiri-1.5.0-java.gem (100%)
Successfully installed nokogiri-1.5.0-java
1 gem installed
11:17:04|dkowis@racktop jruby
$ java -jar jruby-complete-1.6.4.jar -S gem install cucumber --no-rdoc --no-ri
ERROR:  While executing ge开发者_如何学运维m ... (ArgumentError)
    undefined class/module YAML::Syck::DefaultKey
11:18:24|dkowis@racktop jruby
$ java -jar jruby-complete-1.6.4.jar -S gem install cuke4duke --version=0.4.4 --no-rdoc --no-ri
ERROR:  While executing gem ... (ArgumentError)
    undefined class/module YAML::Syck::DefaultKey

There's a couple gems I can install, but the ones I need, I cannot. Is it a problem with the gem itself? Is it a problem with rubygems? I'm not able to puzzle this one out.

This apparently is a known issue with Rubygems reported here on the JRuby Forum.

There is a pull request to fix this Rubygems error, but you could try build the gems you want locally and correct the dependency statements in the gemspec file yourself. I had ran into the same problem with the i18n-js gem.

Hope this helps.