The documentation states versions <= 2.0 are required with ruby 1.8, however the requirement for ruby 1.9 seems to have been introduced as of 1.1.3 (in librarian-puppet.gemspec). Either the documentation should be amended to refer version 1.1.2 being the last supported version on ruby 1.8, or the requirement for ruby 1.9 relaxed to match up with the documentation.
The documentation states versions <= 2.0 are required with ruby 1.8, however the requirement for ruby 1.9 seems to have been introduced as of 1.1.3 (in librarian-puppet.gemspec). Either the documentation should be amended to refer version 1.1.2 being the last supported version on ruby 1.8, or the requirement for ruby 1.9 relaxed to match up with the documentation.