Since #41625, `/guide/updating-to-version-10` is being redirected to
`https://v11.angular.io/guide/updating-to-version-11`. However,
`v11.angular.io` itself is being redirected to `angular.io`, while v11
is the latest stable version. As a result,
`/guide/updating-to-version-10` ends up being redirected to
`https://angular.io/guide/updating-to-version-11`. Currently, this
causes a CI failure in the `aio_monidoting` job ([example failure][1]).
This will change once v12 is released as the new stable version.
Alternatively, we could update the config and tests to expected
`/guide/updating-to-version-10` to be redirected to
`https://angular.io/guide/updating-to-version-11`, but that would end up
being redirected to `https://angular.io/guide/updating-to-version-12`
once v12 would be released, which is different behavior.
This commit provides a way to test for redirects when the destination
URL is itself redirected to a different URL. This allows us to use the
intended URL (for example, `https://v11.angular.io/...`), which will
continue to work as expected regardless of what is the latest stable
version without causing CI failures.
[1]: https://circleci.com/gh/angular/angular/983738
PR Close#42018
04ab5edf65