Fix a buildbot test failure.

test/box/lua.test

@@ -150,9 +150,9 @@ exec admin "lua box.fiber.sleep(box, 0.001)"
 exec admin "lua f = box.fiber.self()"
 exec admin "lua old_id = f:id()"
 exec admin "lua box.fiber.cancel(f)"
-exec admin "lua box.fiber.self():id() == old_id + 2"
+exec admin "lua box.fiber.self():id() == old_id + 1"
 exec admin "lua box.fiber.cancel(box.fiber.self())"
-exec admin "lua box.fiber.self():id() == old_id + 3"
+exec admin "lua box.fiber.self():id() == old_id + 2"
 exec admin "lua g = box.fiber.self()"
 exec admin "lua f==g"
 exec admin "lua function r() f = box.fiber.create(r) return (box.fiber.resume(f)) end"