Handling NoNameservers exception

In the shutdown system test multiple queries are sent to a resolver
instance, in the meantime we terminate the same resolver process for
which the queries were sent to, either via rndc stop or a SIGTERM
signal, that means the resolver may not be able to answer all those
queries, since it has initiated the shutdown process.

The dnspython library raises a dns.resolver.NoNameservers exception when
a resolver object fails to receive an answer from the specified list
of nameservers (resolver.nameservers list), we need to handle this
exception as this is something that may happen since we asked the
resolver to terminate, as a result it may not answer clients even if
an answer is available, as the operation will be canceled.

(cherry picked from commit b19cd2d8)
79 jobs for !5103 with 2282-shutdown-system-test-needs-to-be-tweaked-to-account-for-recent-netmgr-changes-v9_16 in 19 minutes and 47 seconds (queued for 9 seconds)
latest detached
Status Job ID Name Coverage
  Precheck
passed #1752959
amd64 linux
autoreconf

00:00:16

passed #1752961
amd64 linux
clang-format

00:00:17

passed #1752962
amd64 linux
coccinelle

00:03:28

passed #1752963
amd64 linux
danger

00:00:17

passed #1752960
amd64 linux
misc

00:00:17

passed #1752964
amd64 linux
tarball-create

00:00:17

 
  Build
passed #1752978
amd64 linux
clang:asan

00:03:53

passed #1752982
amd64 linux
clang:buster:amd64

00:01:52

passed #1752985
amd64 libvirt
clang:freebsd12:amd64

00:01:47

passed #1752986
amd64 libvirt
clang:freebsd13:amd64

00:03:46

passed #1752987
amd64 libvirt
clang:openbsd:amd64

00:03:18

passed #1752980
amd64 linux
clang:tsan

00:02:20

passed #1752965
amd64 linux
gcc:alpine3.13:amd64

00:01:48

passed #1752977
amd64 linux
gcc:asan

00:03:19

passed #1752975
amd64 linux
gcc:bionic:amd64

00:01:47

passed #1752969
amd64 linux
gcc:buster:amd64

00:01:21

passed #1752966
amd64 linux
gcc:centos7:amd64

00:01:26

passed #1752967
amd64 linux
gcc:centos8:amd64

00:01:32

passed #1752976
amd64 linux
gcc:focal:amd64

00:01:35

passed #1752981
amd64 linux
gcc:mutexatomics

00:01:33

passed #1752971
amd64 linux
gcc:out-of-tree

00:01:23

passed #1752970
amd64 linux
gcc:sid:amd64

00:01:46

passed #1752973
i386 linux
gcc:sid:i386

00:01:26

passed #1752983
amd64 linux
gcc:softhsm2.4

00:01:32

passed #1752984
amd64 linux
gcc:softhsm2.6

00:01:26

passed #1752968
amd64 linux
gcc:stretch:amd64

00:01:35

passed #1752972
amd64 linux
gcc:tarball

00:01:53

passed #1752979
amd64 linux
gcc:tsan

00:01:56

passed #1752974
amd64 linux
gcc:tumbleweed:amd64

00:01:30

passed #1752989
amd64 windows
msvc:windows:amd64

00:00:58

passed #1752988
amd64 linux
nolibtool:sid:amd64

00:02:01

 
  Unit
passed #1753001
amd64 linux
unit:clang:asan

00:01:14

passed #1753005
amd64 linux
unit:clang:buster:amd64

00:00:39

passed #1753008
amd64 libvirt
unit:clang:freebsd12:amd64

00:01:08

passed #1753009
amd64 libvirt
unit:clang:freebsd13:amd64

00:02:58

passed #1753003
amd64 linux
unit:clang:tsan

00:01:32

passed #1752990
amd64 linux
unit:gcc:alpine3.13:amd64

00:00:57

passed #1753000
amd64 linux
unit:gcc:asan

00:01:11

passed #1752998
amd64 linux
unit:gcc:bionic:amd64

00:00:40

passed #1752994
amd64 linux
unit:gcc:buster:amd64

00:00:54

passed #1752991
amd64 linux
unit:gcc:centos7:amd64

00:00:36

passed #1752992
amd64 linux
unit:gcc:centos8:amd64

00:00:37

passed #1752999
amd64 linux
unit:gcc:focal:amd64

00:00:38

passed #1753004
amd64 linux
unit:gcc:mutexatomics

00:00:35

passed #1752995
amd64 linux
unit:gcc:sid:amd64

00:00:37

passed #1752996
i386 linux
unit:gcc:sid:i386

00:00:40

passed #1753006
amd64 linux
unit:gcc:softhsm2.4

00:00:38

passed #1753007
amd64 linux
unit:gcc:softhsm2.6

00:00:40

passed #1752993
amd64 linux
unit:gcc:stretch:amd64

00:00:37

passed #1753002
amd64 linux
unit:gcc:tsan

00:01:43

passed #1752997
amd64 linux
unit:gcc:tumbleweed:amd64

00:00:37

passed #1753010
amd64 linux
unit:nolibtool:sid:amd64

00:01:01

 
  System
passed #1753022
amd64 linux
system:clang:asan

00:14:01

passed #1753026
amd64 linux
system:clang:buster:amd64

00:12:15

passed #1753029
amd64 libvirt
system:clang:freebsd12:amd64

00:10:54

passed #1753030
amd64 libvirt
system:clang:freebsd13:amd64

00:12:44

passed #1753024
amd64 linux
system:clang:tsan

00:15:13

passed #1753011
amd64 linux
system:gcc:alpine3.13:amd64

00:12:12

passed #1753021
amd64 linux
system:gcc:asan

00:13:58

passed #1753019
amd64 linux
system:gcc:bionic:amd64

00:11:47

passed #1753015
amd64 linux
system:gcc:buster:amd64

00:13:19

passed #1753012
amd64 linux
system:gcc:centos7:amd64

00:11:04

failed #1753013
amd64 linux
system:gcc:centos8:amd64

00:12:36

passed #1753020
amd64 linux
system:gcc:focal:amd64

00:11:44

passed #1753025
amd64 linux
system:gcc:mutexatomics

00:12:31

passed #1753016
amd64 linux
system:gcc:sid:amd64

00:12:01

passed #1753017
i386 linux
system:gcc:sid:i386

00:10:10

passed #1753027
amd64 linux
system:gcc:softhsm2.4

00:11:43

passed #1753028
amd64 linux
system:gcc:softhsm2.6

00:12:17

passed #1753014
amd64 linux
system:gcc:stretch:amd64

00:11:37

passed #1753023
amd64 linux
system:gcc:tsan

00:16:03

passed #1753018
amd64 linux
system:gcc:tumbleweed:amd64

00:11:31

passed #1753031
amd64 linux
system:nolibtool:sid:amd64

00:11:47

 
  Docs
passed #1753032
amd64 linux
docs

00:02:28

 
  Postcheck
passed #1753036
amd64 linux
cppcheck

00:00:22

passed #1753033
amd64 linux
flake8

00:00:20

passed #1753037
amd64 linux
gcov

00:00:36

76.0%
passed #1753034
amd64 linux
pylint

00:00:25

passed #1753035
amd64 linux
scan-build

00:09:32

 
Name Stage Failure
failed
system:gcc:centos8:amd64 System
I:The following system tests failed:
I: fetchlimit
make: *** [Makefile:502: test] Error 1
Uploading artifacts for failed job
Uploading artifacts...
untracked: found 1408 files

Uploading artifacts as "archive" to coordinator... ok
id=1753013 responseStatus=201 Created token=fD8pGVry
Cleaning up file based variables
ERROR: Job failed: exit code 1