Fix request #6146 - Backend raise errors about cvs logs while cvs is not even installed

Change-Id: I041e0d2426fa526112f2cad21baa47992255e450
Merge commit 'refs/changes/57/2057/1' of ssh://gerrit.tuleap.net:29418/tuleap into tuleap-stable-master

* ssh://gerrit.tuleap.net:29418/tuleap:
  Fix request #6146 - Backend raise errors about cvs logs while cvs is not even installed

Change-Id: If2b563da66afbc3acbb46400a18547283d8c8177
Tuleap 6.11.99.5

Change-Id: Id9bf2e95af193a1644269fc9c3c40c6f97bbe5bf