yelp-2.19.x, headed into 2.20, uses librarian. That library states that it is "not API-stable yet" and does not do any sort of libtool versioning. Seems risky to have something slated for stable with an external dependency that is self-declaredly not stable with regards to linking against it. I'm not sure what the plans for rarian interface stability are (freezing it and using a standard library versioning at the point of gnome2.20 release vs having everyone "know" that every release version is subject to API/ABI change, etc). I guess technically not a "bug" yet, but will be the instant the rarian interface changes out from under yelp.