original code in `/lib/router/router.js`
```
urlIsNew (pathname, query) {
return this.pathname !== pathname || !shallowEquals(query, this.query)
}
```
the urlIsNew compare `this.pathname` to an argument `pathname`
the invokers:
```
// If asked to change the current URL we should reload the current page
// (not location.reload() but reload getInitialProps and other Next.js stuffs)
// We also need to set the method = replaceState always
// as this should not go into the history (That's how browsers work)
if (!this.urlIsNew(asPathname, asQuery)) {
method = 'replaceState'
}
```
the parameter here is `asPathname` destructured from `asPath`
so here is a problem when we reuse a single page rendered in two asPaths
pages/a.js
```
<>
<Link href='/a'><a>goto a</a></Link>
<Link href='/a' as='/b'><a>goto b</a></Link>
</>
```
If we navigate to page /a, then click 'goto b', actually the history is replaced, not pushed.
It is expected that history could be correctly pushed and popped as long as the browser url is changed.
Currently, using `as` will cause the router to think the URL is not changing in the case where you're re-rendering the same page with a different route. This would most likely be an issue for custom servers
which are using shallow routing.
This should be an invisible change for non-custom-server users, since `as` is defaulted to `url` if not set.
This should resolve#3065.
