request #6963 Incorrect error code REST API

Change-Id: I14711c4869a1afc213b31a2bbeba1573e0eed09f
Merge commit 'refs/changes/34/2634/2' of ssh://gerrit.tuleap.net:29418/tuleap into tuleap-stable-master

* ssh://gerrit.tuleap.net:29418/tuleap:
  request #6963 Incorrect error code REST API

Change-Id: Idf217751628fce20570762aba330b5b2fa9edfec
Tuleap 7.1.99.32

Change-Id: I98d70293889713d7adae61910ad668d6f65525a1