views,models: simplify code computing transitive closure of MailingList models

docbow_project/docbow/models.py

@@ -575,12 +575,11 @@ class MailingListManager(GetByNameManager):
 
     def are_member_of(self, users):
         lists = set(MailingList.objects.filter(members__in=users))
-        count = len(lists)
         while True: # accumulate lists until it grows no more
+            old_count = len(lists)
             lists |= set(MailingList.objects.filter(mailing_list_members__in=lists))
-            if count == len(lists):
+            if old_count == len(lists):
                 break
-            count = len(lists)
         return lists
 
 

docbow_project/docbow/views.py

@@ -69,12 +69,11 @@ def user_mailing_list_names(user):
 
 def recursive_lists(lists):
     lists = set(lists)
-    count = len(lists)
     while True:
+        old_count = len(lists)
         lists |= set(MailingList.objects.filter(members_lists__in=lists))
-        if len(lists) == count:
+        if len(lists) == old_count:
             break
-        count = len(lists)
     return lists
 
 def get_file_form_kwargs(request):