Fix Ugroup deleted and re-created on Gerrit

Change-Id: Ie49b5c284b7c58a090a1ed5d4e014da5b3166b18
Merge commit 'refs/changes/02/402/4' of http://gerrit.tuleap.net/tuleap into stable

* http://gerrit.tuleap.net/tuleap:
  Fix Ugroup deleted and re-created on Gerrit
This is Tuleap 5.12.99.49