Jenkins sends this files as a message body if something failed.

Cc: Sergey Bronnikov <sergeyb@openvz.org>
Fixes: 474f2dfc ("zdtm.py: add option --keep-going")
Signed-off-by: Andrew Vagin <avagin@virtuozzo.com>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>