Fix dump artifact_file efficiency

Change-Id: I07d8155401797df3fe638dd22b8fa36d66e5a58d
Merge commit 'refs/changes/06/906/1' of ssh://gerrit.tuleap.net:29418/tuleap into HEAD

* ssh://gerrit.tuleap.net:29418/tuleap:
  Fix dump artifact_file efficiency

Change-Id: I34784710a1962abde254421baec21518f8a0e533
This is Tuleap 6.4.99.13

Change-Id: I61396b15c388eb3c7555ae76c0c086507de8d653