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.
Seems like the interface is stabilizing, yes? You don't have to freeze it permanently forever into the future, just declare that the current state is ABI 1 or whatever, and then adjust the interface aging and foward/backward-compatibility flags when the interface changes. That way other packages can know what they're dealing with, and maintainers for various package-managers don't go insane.
Rarian is API-unstable until 1.0. Don't know when that will be, but each minor series until then is liable to API changes.
In current SVN Head, I've defined an error unless
#error Rarian is unstable. To use it, you must acknowledge that
This is (ironically) one of the lessons I've learned while writing rarian.
I don't really know about libtool versioning, but I will get it sorted properly during this release cycle.