Jenkins complains about missing plugins

[bascht]

Hi. I am new to jenkins.rb - so perhaps its my fault, but with a default installation (gem install jenkins) - I cannot play through the tutorials because the Git and Ruby Plugin of jenkins is missing:

WARNING: Failed to resolve class
com.thoughtworks.xstream.mapper.CannotResolveClassException: hudson.plugins.ruby.Ruby : hudson.plugins.ruby.Ruby

Everything works fine if I install the plugins manually via the Jenkins web frontend.

Am I missing something here?