prefer !x.exists? instead of x.none? to prevent unnecessary instantiation of records

app/models/group.rb

@@ -129,11 +129,11 @@ class Group < Namespace
   end
 
   def visibility_level_allowed_by_projects?(level = self.visibility_level)
-    projects.where('visibility_level > ?', level).none?
+    !projects.where('visibility_level > ?', level).exists?
   end
 
   def visibility_level_allowed_by_sub_groups?(level = self.visibility_level)
-    children.where('visibility_level > ?', level).none?
+    !children.where('visibility_level > ?', level).exists?
   end
 
   def visibility_level_allowed?(level = self.visibility_level)