All the other Markdown engines are conditionally included, but Maruku is loaded by jekyll.rb whether it is going to be used or not. Saves time and space for configurations that don't use Maruku!
Remove MaRuKu from the always-required modules.
@parkr Isn't Maruku the default markdown engine?
Yeah, MaRuKu is default. We'll need to leave it in there, unfortunately.