Merge branch 'port-missing-code-from-ee-in-group_policy' into 'master'

Add a missing policy allowance in GroupPolicy

See merge request gitlab-org/gitlab-ce!23906

app/policies/group_policy.rb

@@ -40,6 +40,7 @@ class GroupPolicy < BasePolicy
 
   rule { guest }.policy do
     enable :read_group
+    enable :read_list
     enable :upload_file
     enable :read_label
   end