Comment 1 for bug 1996134

The offending line is:
  678 out = subprocess.check_output(['resolvectl', 'query', 'math.lab'])

With -1006:
$ sudo pdb3 ./networkd-test.py
> /home/ubuntu/systemd-249.11/test/networkd-test.py(21)<module>()
-> import errno
(Pdb) b 678
Breakpoint 1 at /home/ubuntu/systemd-249.11/test/networkd-test.py:678
(Pdb) c
systemd-network:x:100:102:systemd Network Management,,,:/run/systemd:/usr/sbin/nologin
test_bridge_init (__main__.BridgeTest) ... ok
test_bridge_port_priority (__main__.BridgeTest) ... ok
test_bridge_port_priority_set_zero (__main__.BridgeTest)
It should be possible to set the bridge port priority to 0 ... ok
test_bridge_port_property (__main__.BridgeTest)
Test the "[Bridge]" section keys ... ok
test_coldplug_dhcp_ip4_only (__main__.DnsmasqClientTest) ... ok
test_coldplug_dhcp_ip4_only_no_ra (__main__.DnsmasqClientTest) ... ok
test_coldplug_dhcp_ip6 (__main__.DnsmasqClientTest) ... ok
test_coldplug_dhcp_yes_ip4 (__main__.DnsmasqClientTest) ... ok
test_coldplug_dhcp_yes_ip4_no_ra (__main__.DnsmasqClientTest) ... ok
test_hotplug_dhcp_ip4 (__main__.DnsmasqClientTest) ... ok
test_hotplug_dhcp_ip6 (__main__.DnsmasqClientTest) ... ok
test_resolved_domain_restricted_dns (__main__.DnsmasqClientTest)
resolved: domain-restricted DNS servers ... > /home/ubuntu/systemd-249.11/test/networkd-test.py(678)test_resolved_domain_restricted_dns()
-> out = subprocess.check_output(['resolvectl', 'query', 'math.lab'])
(Pdb)

(in another terminal)
ubuntu@curly:~$ resolvectl query math.lab
math.lab: 10.241.3.3 -- link: testvpnrouter

-- Information acquired via protocol DNS in 10.4732s.
-- Data is authenticated: no; Data was acquired via local or encrypted transport: no
-- Data from: network

With -1007
$ sudo pdb3 ./networkd-test.py
> /home/ubuntu/systemd-249.11/test/networkd-test.py(21)<module>()
-> import errno
(Pdb) b 678
Breakpoint 1 at /home/ubuntu/systemd-249.11/test/networkd-test.py:678
(Pdb) c
systemd-network:x:100:102:systemd Network Management,,,:/run/systemd:/usr/sbin/nologin
test_bridge_init (__main__.BridgeTest) ... ok
test_bridge_port_priority (__main__.BridgeTest) ... ok
test_bridge_port_priority_set_zero (__main__.BridgeTest)
It should be possible to set the bridge port priority to 0 ... ok
test_bridge_port_property (__main__.BridgeTest)
Test the "[Bridge]" section keys ... ok
test_coldplug_dhcp_ip4_only (__main__.DnsmasqClientTest) ... ok
test_coldplug_dhcp_ip4_only_no_ra (__main__.DnsmasqClientTest) ... ok
test_coldplug_dhcp_ip6 (__main__.DnsmasqClientTest) ... ok
test_coldplug_dhcp_yes_ip4 (__main__.DnsmasqClientTest) ... ok
test_coldplug_dhcp_yes_ip4_no_ra (__main__.DnsmasqClientTest) ... ok
test_hotplug_dhcp_ip4 (__main__.DnsmasqClientTest) ... ok
test_hotplug_dhcp_ip6 (__main__.DnsmasqClientTest) ... ok
test_resolved_domain_restricted_dns (__main__.DnsmasqClientTest)
resolved: domain-restricted DNS servers ... > /home/ubuntu/systemd-249.11/test/networkd-test.py(678)test_resolved_domain_restricted_dns()
-> out = subprocess.check_output(['resolvectl', 'query', 'math.lab'])
(Pdb)

(in another terminal)
ubuntu@curly:~$ resolvectl query math.lab
math.lab: resolve call failed: Lookup failed due to system error: No route to host