zdtm/chroot: wait when a child closes a descriptor

A static test should not change its state during C/R.
Signed-off-by: Andrew Vagin <avagin@virtuozzo.com>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>

test/zdtm/live/static/chroot.c

@@ -78,6 +78,7 @@ int main(int argc, char **argv)
 
 		res = ERR_PIPES;
 		read(pipe_prep[0], &res, 1);
+		read(pipe_prep[0], &res, 1); /* wait when pipe_prep[] will be closed */
 		if (res != SUCCESS) {
 			if (res == ERR_PIPES)
 				pr_perror("broken pipes");