request #7529: Errors with System Event when the queue is unknown

Instead of executing the default queue as root, the given queue should
be ignored.

We can have an unknown queue when a plugin is deactivated. (Eg: fts)

Change-Id: I9163a9bbf73c148a1cf074b37bd540c2a255b9ab
Merge commit 'refs/changes/31/3131/1' of ssh://gerrit.tuleap.net:29418/tuleap into HEAD

* ssh://gerrit.tuleap.net:29418/tuleap:
  request #7529: Errors with System Event when the queue is unknown

Change-Id: I5ab6017053de56714084de35920f5e1e824aad08
This is Tuleap 7.5.99.74

Change-Id: I160befc34933a880f3f7e7084b2218692b18b495