don't rewrite cached SOA records from negative answers

Currently there's only exception to avoid rewriting secure NS records.
Most of the negative answers provide SOA record, so it's undesirable
to keep rewriting it for every negative answer.
18 jobs from marek/dont-rewrite-soa-records in 8 minutes and 11 seconds (queued for 10 seconds)
latest
Status Job ID Name Coverage
  Build
passed #136426
docker linux amd64
build:clang:linux:amd64

00:00:39

passed #136425
docker linux amd64
build:linux:amd64

00:00:40

passed #136427
docker linux amd64 allowed to fail
srpm

00:00:25

 
  Test
passed #136434
docker linux amd64
deckard:linux:amd64

00:07:05

passed #136441
privileged
distro:epel-7

00:03:06

passed #136440
privileged
distro:fedora-27

00:03:58

passed #136433
docker
doc

00:00:50

passed #136432
docker linux amd64
installcheck:linux:amd64

00:01:12

passed #136435
docker linux amd64
installcheck:valgrind:linux:amd64

00:01:49

passed #136429
docker
lint:c

00:02:38

failed #136430
docker allowed to fail
lint:clang-scan-build

00:01:20

passed #136428
docker
lint:lua

00:00:50

passed #136438
docker linux amd64
respdiff:iter:tcp:linux:amd64

00:03:54

passed #136439
docker linux amd64
respdiff:iter:tls:linux:amd64

00:03:53

passed #136437
docker linux amd64
respdiff:iter:udp:linux:amd64

00:04:00

passed #136431
docker linux amd64
test:linux:amd64

00:01:29

passed #136436
docker linux amd64
test:linux:amd64:valgrind

00:01:25

 
  Coverage
passed #136442
docker linux amd64
coverage

00:00:22

69.1%
 
Name Stage Failure
failed
lint:clang-scan-build Test
                                             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
5 warnings generated.
CCLD daemon/kresd
scan-build: 28 bugs found.
scan-build: Run 'scan-view /builds/knot/knot-resolver/scan-results/2018-05-12-042436-14-1' to examine bug reports.
Uploading artifacts...
scan-results: found 33 matching files
Uploading artifacts to coordinator... ok id=136430 responseStatus=201 Created token=zQkPZyX_
ERROR: Job failed: exit code 1