Reproduction

https://github.com/syenet/vue-test

Steps to reproduce the bug

1. visit /a in browser to 'a' list page.
2. in 'a' list page, click the link 'Go to /a/123' to visit detail page of 'a 123'.
3. in 'a 123' detail page, click the link 'b/' to visit 'b' list page.
4. in 'b' list page, click the link 'page=2'.
5. note that onBeforeRouteUpdate is not triggered.
6. now, if you visit '/a' again, the issue is gone, click 'page=2', onBeforeRouteUpdate will be triggered as expected from now on.
7. now you can visit '/b' again, click 'page=2', onBeforeRouteUpdate will be triggered as well.

Expected behavior

at step 5, onBeforeRouteUpdate should be triggered.

Actual behavior

at step 5, onBeforeRouteUpdate is not triggered.

Additional information

No response