Happened because LOCK method was not allowed without credentials.

Change-Id: I7b204e67079791a08211410ced4b0b4f015d524a
Reviewed-on: https://gerrit.libreoffice.org/17856Reviewed-by: Jan Holesovsky <kendy@collabora.com>
Tested-by: Jan Holesovsky <kendy@collabora.com>