Use 'set -u' in gettextized shell scripts
So far we’ve been avoiding it, see e.g. this comment from
# Do not "set -u", else importing gettext.sh dies # with "ZSH_VERSION: parameter not set".
However, we can actually
set -u as long as we set:
gettext.sh in each such script (see
git grep "\. gettext\.sh" for a list of candidates).
Feature Branch: feature/9371-set-u-in-gettextized-shell-scripts
Parent Task: #9372