test-network: add one more testcase for DHCPv4 classless route

For issue #28280.

(cherry picked from commit 86f6760)
(cherry picked from commit f74337b)
(cherry picked from commit 7cf1bc0)

Author: yuwata

test/test-network/systemd-networkd-tests.py

@@ -4557,7 +4557,7 @@ def _test_dhcp_client_ipv4_use_routes_gateway(self, use_routes, use_gateway, dns
         self.wait_online(['veth-peer:carrier'])
         additional_options = '--dhcp-option=option:dns-server,192.168.5.10,8.8.8.8 --dhcp-option=option:ntp-server,192.168.5.11,9.9.9.9 --dhcp-option=option:static-route,192.168.5.100,192.168.5.2,8.8.8.8,192.168.5.3'
         if classless:
-            additional_options += ' --dhcp-option=option:classless-static-route,0.0.0.0/0,192.168.5.4,8.0.0.0/8,192.168.5.5'
+            additional_options += ' --dhcp-option=option:classless-static-route,0.0.0.0/0,192.168.5.4,8.0.0.0/8,192.168.5.5,192.168.5.64/26,192.168.5.5'
         start_dnsmasq(additional_options=additional_options, lease_time='2m')
         self.wait_online(['veth99:routable', 'veth-peer:routable'])
 
@@ -4569,6 +4569,7 @@ def _test_dhcp_client_ipv4_use_routes_gateway(self, use_routes, use_gateway, dns
             if classless:
                 self.assertRegex(output, r'default via 192.168.5.4 proto dhcp src 192.168.5.[0-9]* metric 1024')
                 self.assertRegex(output, r'8.0.0.0/8 via 192.168.5.5 proto dhcp src 192.168.5.[0-9]* metric 1024')
+                self.assertRegex(output, r'192.168.5.64/26 via 192.168.5.5 proto dhcp src 192.168.5.[0-9]* metric 1024')
                 self.assertRegex(output, r'192.168.5.4 proto dhcp scope link src 192.168.5.[0-9]* metric 1024')
                 self.assertRegex(output, r'192.168.5.5 proto dhcp scope link src 192.168.5.[0-9]* metric 1024')
             else: