errno is no guaranteed to be clear if call exit with
success. Thus make sure we've ret negative here and
test for errno then.

http://bugzilla.openvz.org/show_bug.cgi?id=2412Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>