fix systemd output parsing

tests/test_dns_records.py

@@ -17,8 +17,6 @@ from envsetup import utils as u  # noqa: E402
 
 
 def get_dns_servers() -> set:
-    servers = list()
-
     if subprocess.getstatusoutput("command -v nmcli")[0] == 0:
         # network-manager
         _, output = subprocess.getstatusoutput(
@@ -34,6 +32,7 @@ def get_dns_servers() -> set:
 
     if "127.0.0.53" in servers:
         # systemd-resolved
+        servers = list()
         _, output = subprocess.getstatusoutput("systemd-resolve --status")
         lines = [l.strip() for l in output.split("\n")]
         dns_line = False