Actually this test case is a frame work for creating a process tree.
It creates a process tree according with a predefined sequence of
actions.

This test case create the following process tree:
  5     5  \_ session02               ( 0)
  6     6      \_ session02           ( 1)
  8     7      |   \_ session02       ( 3)
 15    12      |   \_ session02       (10)
 10    10      \_ session02           ( 5)
 11     7          \_ session02       ( 6)
 13    12          \_ session02       ( 8)

v2: improve log messages
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>