There is a Repository class under models/ (I'll call it A) and another Repository under publishing/ (call it B). Mentions of Repository in fast.rb and slurb.rb used to resolve correctly to A, but on my instance I just had those same mentions resolve to B, causing the operation (publishing i think) to fail. This might be due to the recent ruby upgrade, I don't know.
My fix was to rename class A, but perhaps there is a way to force those mentions to resolve to A without changing the name of the class.