fix ICMP packet checker

10 jobs for <span class="ref-name">non-existent-ip</span> in 1 minute and 27 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Test
passed #215840
docker linux amd64
test:augeas

00:00:27

passed #215846
docker linux amd64
test:comparative:kresd

00:01:23

passed #215841
docker linux amd64
test:flake8

00:00:19

passed #215847
docker linux amd64
test:latest:kresd

00:01:07

passed #215842
docker linux amd64
test:mypy

00:00:27

passed #215843
docker linux amd64
test:pylint

00:00:26

passed #215844
docker linux amd64
test:rplint

00:00:20

passed #215849
docker linux amd64
test:sanity:pdnsrecursor

00:00:29

passed #215848
docker linux amd64
test:sanity:unbound

00:00:28

passed #215845
docker linux amd64
test:unittests

00:00:21