bug: relative navigation doesn't work inside route guards #22763

I'm submitting a...

[x] Bug report  

Current behavior

Inside a route guard, injecting ActivatedRoute and attempting relative navigation via this.router.navigate(['../sibling'], {relativeTo: this.route}) results in a Error: Cannot match any routes. URL Segment: 'sibling'

Expected behavior

Relative navigation should work normally

Minimal reproduction of the problem with instructions

A stackblitz example of the issue can be seen here: https://stackblitz.com/edit/angular-gitter-k7fjds

What is the motivation / use case for changing the behavior?

1. This appears to be a bug
2. If a user navigates to a child route and includes a specific queryParam, I'd like to redirect the user to a sibling route. Currently, this does not appear to be possible inside a route guard with relative navigation.

Additional Information

It appears that the ActivatedRoute injected into a route guard is always an instance of the root route. Inside a route guard, this.router.navigate(['.'], {relativeTo: this.route}) always takes the user back to the root route, rather than navigating them to the same route they are currently on.

Environment

Angular version: 5.0.0


Browser:
- [x] Chrome (desktop) version 64