The Query class insists there must be a NS record at the origin, so adding one. It points to non-existing A record, but that does not seem to be a problem (and the NS makes no sense in this case anyway).
@@ -6,7 +6,9 @@
;;
;; in the bindctl.
+;; This is here mostly for technical reasons.
BIND. 0 CH SOA bind. authors.bind. 0 28800 7200 604800 86400
+BIND. 0 CH NS BIND.
VERSION.BIND. 0 CH TXT "@@VERSION_STRING@@"
;; HOSTNAME.BIND 0 CH TXT "localhost"