Fix an error when the brokerlink's return value has no data

This could happen during setup or the first execution of
included daemons. The metadata file was present, but nobody
has reported anything yet.

Change-Id: I0f1e96595ca07c20bae6fba805ae2bc4ba3e5151
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=1075126
Signed-off-by: Martin Sivak <msivak@redhat.com>