This test makes sure, that processes tree is restored before opened files.
This is guaranteed by holding child's "/proc/<pid>/stat" file opened by parent.

It was inspired by OpenVZ bug:
#2404

IOW, OpenVZ can't restore container with such test inside.

v2:
1) Test renamed + carefull cleanup + minor updates.
Signed-off-by: Stanislav Kinsbursky <skinsbursky@openvz.org>
Acked-by: Andrew Vagin <avagin@parallels.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>