kdig ignores DoQ response from dnsdist

kdig +quic @doq.dns4all.eu example.com says ;; ERROR: failed to query server doq.dns4all.eu@853(UDP). dns4all uses dnsdist for DoQ. The same problem was initially reported to me with a private dnsdist instance.

kdig versions before 3.4.0 work. A bisect points to bd75c1fe. Building 3.4.0 with that patch reverted makes the query work.

In strace, I see kdig does receive a response packet - it just does not appear to like it.

I don't know if this is a -bug- in kdig, or whether the change in that commit exposes a dnsdist problem.