fish: arrows and backspace keys no longer supported after 11.0-RELEASE upgrade

[David Guyot]

Hello, there.

I was using a 10.3-RELEASE FreeBSD with the packaged fish 2.2.0
installed, without customization, and upgraded my system and packages
to 11.0-RELEASE. fish were upgraded to 2.3.1, and I lost the previous
default prompt, but that doesn't really matter. My main problem is that
it lost support of arrows and backspace keys: whenever I try to use
them, I get this:
# Up arrow for autocompletion with the last command
penegal at Aethelthryth-FreeBSD~/usr/home/penegal> [A
# Right arrow for autocompletion with the last similar command, then
# left arrow to correct input
penegal at Aethelthryth-FreeBSD~/usr/home/penegal> ls[C[D

Tab still functions as usual; backspace produces no result, so I have
to Ctrl+C to erase the line and restart the typing from the start. As I
also use fish as the root shell, the problem persists when using sudo
su, but not with su -; the problem is also present when using fish from
vt, and the su tweak works all the same. bash doesn't have this problem
and responds as usual to these keys, as do fish over SSH connections,
so it's not keyboard-related.

I suspect a configuration that broke upon the upgrade, but am unsure
about it, and the fish changelog doen't seem to have anything related,
but I'm not accustomed to its internals and can have missed it. Does
somebody have suggestions?

Awaiting your answers,

Regards.
-- 
David Guyot
Administrateur système, réseau et télécom / Sysadmin
Europe Camions Interactive / Stockway
Moulin Collot
F-88500 Ambacourt
03 29 30 47 85