After upgrading to 2.14, manually merged books split apart and asset folders are duplicated

Books where I had manually merged an ebook and an audiobook now show the audiobook listed separately in the library. On disk I have two or three asset folders for the same title — one with a trailing dash, one without, and one with a short suffix in brackets — and some .epub files are simply gone, leaving folders with only a cover image.

Resolution: The asset folder naming function was changed (among other things, it stopped leaving a trailing dash on sanitized titles), and the migration that renames existing folders did not cover every configuration, so affected books ended up with a new folder while the old one was orphaned — which the library then presents as separate, unmerged entries. Folder naming is much more stable after this change, so the breakage is one-time rather than ongoing. To clean up: update to a current release, delete the duplicate/orphaned entries and their stale asset folders, and re-import the affected books. Back up your data directory before deleting anything, since some of those orphaned folders are the ones still holding the original .epub.