Change NTP test for Debian (refs #27160).

tests/test_ntp.py

@@ -52,7 +52,7 @@ if not expected_servers:
     if 'Ubuntu' in subprocess.getoutput('lsb_release -a'):
         expected_servers = ['ntp.ubuntu.com']
     else:
-        expected_servers = ['0.debian.pool.ntp.org']
+        expected_servers = ['0.debian.pool.ntp.org iburst']
 
 with open(ntpconf, 'r') as f:
     content = f.read()