Fix request #4305 - Warnings when a plugin is installed

Change-Id: Iff9a35bdcda51d4a53161a877b8c6f5b867d1cab
Merge commit 'refs/changes/21/1621/1' of http://gerrit.tuleap.net/tuleap into HEAD

* http://gerrit.tuleap.net/tuleap:
  Fix request #4305 - Warnings when a plugin is installed

Change-Id: I10ad5924e1c68cc900f9d34ddf2d728a666d1f0e
Tuleap 6.8.99.17

Change-Id: Id42976a8ede581597df912e03ad0518e63c30eca