Resolves: fdo#86843 avoid getting deleted before finishing Broadcast

Change-Id: I19181f9e2fbd5f906e6e5d807b1b2483e7881cf0
(cherry picked from commit 19d0950451f909086c3732ce29812c4cda513908)
Reviewed-on: https://gerrit.libreoffice.org/13420
Reviewed-by: Miklos Vajna <vmiklos@collabora.co.uk>
Tested-by: Miklos Vajna <vmiklos@collabora.co.uk>