Comment 8 for bug 1376590

I dropped that codepath entirely in vivid in 1.17.23ubuntu1, since it was only meant for transitions to trusty anyway. Ubuntu doesn't do point releases the same way as Debian (we don't merge -updates down into the release pocket at point releases), so fixing this for T/U will do no one any measurable amount of good, so I'll just WontFix the old releases.