Extend "Select non branching way sequences" to "Select non branching relation sequences"

[Nielkrokodil]

To map public transport routes I often use Shift+W to select multiple way segments along the route. Pretty often there are multiple bus routes following the same streets for some time, across intersections where (minor) roads branch off. By filtering out footways and cycleways the necessary clicking can be reduced, but especially in built-up areas it still is a lot to zoom and click tonjust follow an existing bus route.

It would be great if there was another command, like Shift+W+W to extend the selection from "non branching ways" to "non branching (bus) relations"