Debian Live: no default user?

[Borden Rhodes <jrvp@bordenrhodes.com>]

Greetings. I have the stretch versions of live-build, live-boot and
live-config on my system. Please find my auto/config file below. I
have not fiddled with any other files in my auto/ or config/ folder
trees. The resulting image has no loginable user. I understand from
http://live.debian.net/manual/stable/html/live-manual.en.html#503 that
the default user should be 'user' and the password 'live'. I also
understand that I can customise this by setting --bootappend-live.
However, why is this not working for me in the default case?

With thanks,

auto/config:
#!/bin/sh
DISTRIBUTION=jessie

set -e

lb config noauto \
    --clean \
    --architecture i386 \
    --linux-flavours "amd64 586" \
    --distribution ${DISTRIBUTION} \
    --firmware-binary true \
    --debian-installer live \
    --memtest memtest86+ \
    --apt aptitude \
    --apt-indices false \
    --apt-recommends false \
    --archive-areas main contrib non-free \
    --updates true \
    --security true \
    --backports true \
    --debconf-frontend dialog \
    "${@}"