/usr/lib/freedombox/setup.d/01_etckeeper-pre is in freedombox-setup 0.8ubuntu1.
This file is owned by root:root, with mode 0o755.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13  | #!/bin/sh
# Avoid etckeeper problem (refuses to commit) because git picked a
# email address with an empty domain.
if which etckeeper > /dev/null 2>&1 && \
    [ ! -e /etc/mailname ] &&
    [ -z "$(git config --global --get user.email)" ] ; then
    echo "info: Setting git user.email."
    git config --global user.email "root@localhost"
    etckeeper commit -m "Status before freedombox-setup run."
else
    echo "info: Not setting git user.email."
fi
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