empty non-terminal causes drill validation to terminate prematurely

[pspacek]

Version: ldns 1.7.1

It seems that empty non-terminal causes drill -DT to terminate walk-down prematurely. Example:

drill -DT child-short-ttl.nsreval.testiscorg.ch. NS

nsreval.testiscorg.ch. NS does not exist, but child-short-ttl.nsreval.testiscorg.ch. NS does exist and it is a signed delegation. and drill -DT exists with this message:

[T] child-short-ttl.nsreval.testiscorg.ch. 86400 IN DS 28064 13 2 3c0dae643d96d802150f52bb37d873aa14caea6413f9b50aa83cb2ed80741d3a 
[T] Existence denied: nsreval.testiscorg.ch. NS

Asking a normal recursive resolver gives back:

$ dig child-short-ttl.nsreval.testiscorg.ch. NS
;; ANSWER SECTION:
child-short-ttl.nsreval.testiscorg.ch. 5 IN NS	ns2.isc.org.
child-short-ttl.nsreval.testiscorg.ch. 5 IN RRSIG NS 13 4 15 20371231235959 20250425121245 28064 child-short-ttl.nsreval.testiscorg.ch. [omitted]

so I would think drill -DT should get to this RR as well.

Full log: log.txt

The domain is live and should stay there for forseable future. If you want zone files I can provide them as well.