Thank you. I also learned ruby with the ruby koans and was lucky enough to meet him through our local ruby community and eventually end up working with him. His other free and open-source educational work was git immersion: http://gitimmersion.com/ which you might like.

Also, here's one of my favorite practices to watch Jim do & to practice as well: http://www.youtube.com/watch?v=ronr_CG8x0Y

Thanks for the bug report, I'm opening an issue. Can you email me a screenshot? email address in profile.