Almquist shell shipped with FreeBSD echoes Unicode input with bell chars. Despite that, it prints them fine in name completion. NetBSD sh -- which I think is Almquist, too -- works without any additional setup.
Tested in xterm and rxvt-unicode.
Pinned the problem to LC_CTYPE. Setting it to "ru_RU.KOI8-R" seems to relieve the symptom for Russian characters.
SVN r276881 fixed this in 11-current (in the underlying libedit library). This commit has a MFC after field.
Unfortunatly MFCing would be complicated, I don't know if I'll end up doing it.
For bugs matching the following conditions:
- Status == In Progress
- Assignee == "bugs@FreeBSD.org"
- Last Modified Year <= 2017
- Set Status to "Open"
Apparently, MFC didn't happen. Closing this as fixed by base r276881 in all supported (at the moment) branches.