This error happens if we are not able to close the pipe to the
parent (to trace errors in the child process) and assign stderr to
/dev/null as required by the daemonizing convention.

Signed-off-by: Denis V. Lunev <den@openvz.org>
Suggested-by: Eric Blake <eblake@redhat.com>
CC: Eric Blake <eblake@redhat.com>
CC: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Message-ID: <20230906093210.339585-2-den@openvz.org>
Reviewed-by: Eric Blake <eblake@redhat.com>
[eblake: commit message grammar]
Signed-off-by: Eric Blake <eblake@redhat.com>