I've posted a longer explanation in https://news.ycombinator.com/item?id=44991638. I'm interested to hear which kernel and which firesystem zimpenfish is using that has this problem.
I believe macOS forces UTF-8 filenames and normalizes them to something near-but-not-quite Unicode NFD.
Windows doing something similar wouldn't surprise me at all. I believe NTFS internally stores filenames as UTF-16, so enforcing UTF-8 at the API boundary sounds likely.
