This test fails when run in ns:

(00.300947)      1: Error (util.c:568): exited, status=1
(00.300964)      1: Error (cr-restore.c:1067): 5 exited, status=1
(00.300989)      1: Error (mount.c:637): Can't restore tmpfs content
(00.301005) Error (cr-restore.c:1602): Restoring FAILED.

Reason for failure -- tar is spawned in new mount namespace where
it can not be found (bug #2870).
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>