dns64: workaround for broken auths which fail on AAAA query

Some auths return weird stuff on AAAA query and RFC 6147 section-5.1.2
mandates workarounds for these cases.

This is only partial fix.
In some cases all servers return answers so weird that iterator refuses
to accept them and fails with "no NS" condition, which in turn does not
call consume phase and skips dns64 module.
Fixing this particular case will require changes to module logic and
such change is not suitable to minor release.

Related: #483
28 jobs for 483-dns64-aaaa-failures-fix in 5 minutes and 35 seconds (queued for 3 seconds)
latest
Status Job ID Name Coverage
  Build
passed #308990
amd64 linux docker
archive

00:00:52

passed #308991
amd64 linux docker
build

00:00:59

passed #308992
amd64 linux docker
build-asan

00:01:01

passed #308993
docker
kres-gen

00:00:55

 
  Test
passed #308994
docker delayed
build:darwin

00:00:26

failed #309020
amd64 linux docker
deckard

00:01:30

passed #308996
docker delayed
doc

00:01:10

passed #308997
dind
docker

00:02:28

passed #308998
docker delayed
lint:other

00:00:56

passed #308999
amd64 linux docker delayed
lint:pedantic

00:01:14

passed #309000
amd64 linux docker
lint:scan-build

00:03:06

passed #309001
amd64 linux docker
lint:tidy

00:03:36

passed #309002
privileged
pkg:epel-7

00:02:05

passed #309003
privileged
pkg:fedora-29

00:02:50

passed #309004
amd64 linux docker
respdiff:basic

00:02:41

passed #309005
amd64 linux docker delayed
test:valgrind

00:02:05

failed #308995
amd64 linux docker
deckard

00:03:03

 
  Extended
skipped #309007
respdiff
fwd-tls6-kresd.udp6
skipped #309008
respdiff
fwd-udp6-kresd.udp6
skipped #309012
respdiff
fwd-udp6-unbound.tcp6
skipped #309013
respdiff
fwd-udp6-unbound.tls6
skipped #309011
respdiff
fwd-udp6-unbound.udp6
skipped #309010
respdiff
iter.tls6
skipped #309009
respdiff
iter.udp6
skipped #309006
amd64 linux docker
pytests
skipped #309014
respdiff
resperf:fwd-tls6.udp-asan
skipped #309015
respdiff
resperf:fwd-udp6.udp-asan
skipped #309016
respdiff
resperf:iter.udp-asan
 
Name Stage Failure
failed
deckard Test
WARNING: File ignored:tmpdeckardw0iw19i9/Q7F00000C0035 
WARNING: File ignored:tmpdeckardw0iw19i9/QC1000E810035
WARNING: File ignored:tmpdeckardw0iw19i9/RFD0701200000000000000000010000000035
WARNING: File ignored:tmpdeckardw0iw19i9/W7F00000C0035
WARNING: File ignored:tmpdeckardw0iw19i9/W7F00000C1389
WARNING: File ignored:tmpdeckardw0iw19i9/W7F00000C138A
WARNING: File ignored:tmpdeckardw0iw19i9/WC1000E810035
Uploading artifacts to coordinator... ok
id=309020 responseStatus=201 Created token=YRNRS2Pc
ERROR: Job failed: exit code 1