Every task and helper have ids populated, except this case.
Fix that.

https://travis-ci.org/tkhai/criu/builds/197728925

travis-ci: success for files: Fix not populated helper ids
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>