Fix fatal error on docman notifications. A consequence of this error is that date reminders are not sent-out.

Change-Id: I8099a681fadff3a6f73fbb3e54064783e7ac4711
Merge commit 'refs/changes/67/1567/1' of http://gerrit.tuleap.net/tuleap into HEAD

* http://gerrit.tuleap.net/tuleap:
  Fix fatal error on docman notifications. A consequence of this error is that date reminders are not sent-out.

Change-Id: I5fb30210c86f2af4a5f7c201e3b56ae6079880c4
This is Tuleap 6.8.99.8

Change-Id: I877fad868f9780845f42629a83f42b7bd87548f7