--no-dns does not work

Installing a slave mail server I used the --no-dns option, but bind9 was still installed and the name server is running locally.

Full options used are: ./ispc3-ai.sh --debug --channel=dev --interactive --use-php=system --no-web --no-dns --no-roundcube --no-pma --no-mailman

Output does show bind9 being installed:

[INFO] Installing packages dnsutils, resolvconf, clamav, clamav-daemon, unzip, bzip2, arj, nomarch, lzop, cabextract, apt-listchanges, libnet-ld
ap-perl, libauthen-sasl-perl, clamav-docs, daemon, libio-string-perl, libio-socket-ssl-perl, libnet-ident-perl, zip, libnet-dns-perl, libdbd-mys
ql-perl, bind9, dnsutils, spamassassin, rspamd, redis-server, postgrey, p7zip, p7zip-full, unrar, lrzip
[INFO] Installed packages dnsutils, resolvconf, clamav, clamav-daemon, unzip, bzip2, arj, nomarch, lzop, cabextract, apt-listchanges, libnet-lda
p-perl, libauthen-sasl-perl, clamav-docs, daemon, libio-string-perl, libio-socket-ssl-perl, libnet-ident-perl, zip, libnet-dns-perl, libdbd-mysq
l-perl, bind9, dnsutils, spamassassin, rspamd, redis-server, postgrey, p7zip, p7zip-full, unrar, lrzip
[INFO] Stopping Rspamd.
[INFO] (Re)starting Bind.
[INFO] Disabling spamassassin daemon.
[INFO] Checking local dns resolver.
[WARN] Unexpected resolver response: Server:            xx.xx.xx.xx (/lib/os/class.ISPConfigDebianOS.inc.php:703)

At this point, 127.0.0.1 has been added to /etc/resolv.conf, and name resolution is pretty broken (a firewall restricts dns requests to the correct, and previously in use, local name servers).