@d.ian.b no clue. Best guess the author moved on (appengine has its quirks). There are some new light alternatives.
As far as i can tell appengine is moving away from dev_server and dropping a hunch of services (search, tasks, image api). So might not be a need for stuff like that. Java seems to be lagging a bit vs the other envs. Personally going with nodejs(clojurescript), seems like a better fit and more up to date with the direction appengine is going