Minor changes

clusterman/commands/frontend.py

@@ -26,9 +26,10 @@ def info():
                 print(", ", end="")
             pattern = re.compile(CONF["cluster"]["groups"][group])
             count=0
-            for ip in nodes:
-                if pattern.match(ip):
-                    count=count+1
+            if not nodes == None:
+                for ip in nodes:
+                    if pattern.match(ip):
+                        count=count+1
             print("{}({})".format(group,count),end="")
         print()
     else: