Since set -u is used, without bash or perl, configure would fail.
This has gone unnoticed as (almost) everyone always had both
bash and perl installed (and in $PATH).
Thanks to FreeBSD ports this bug became visible; this change is
verbatim copy of `patch-configure` in FreeBSD ports tree.
printf "Yes (%s).\n" "$bash_absolute"
else
have_bash=0
+ bash_absolute=
printf "No. (%s not found)\n" "${BASHCMD}"
fi
printf "Yes (%s).\n" "$perl_absolute"
else
have_perl=0
+ perl_absolute=
printf "No. (%s not found)\n" "${PERL}"
fi