fix relay parser, #20590

tests/test_postfix.py

@@ -29,7 +29,7 @@ all_ok = True
 def get_configured_relay():
     status, out = subprocess.getstatusoutput('grep relayhost /etc/postfix/main.cf')
     if status == 0:
-        return out.split('relayhost =')[1]
+        return out.split('relayhost = ')[1]
 
 def check_relay():
     global all_ok