I just realized that every time Ettus updates UHD in their PPA, it replaces the previous version, practically breaking all binary packages that were built using the previous version. I think this happens because the package name is libuhd003 regardless of the version number, and so they can only have one version installed at a time.
I have filed an issue just to make sure they are aware of this.
Of course this makes me think that our PPA should not depend on the Ettus PPA but either use the version available in Ubuntu or we should import a version in our drivers PPA and update at our own convenience. Otherwise our PPA will keep breaking every time the fix a spelling error