Set permissions link from Roles page doesn't apply role filter

[yorkshire-pudding]

Steps to reproduce

1. Navigate to the /admin/config/people/roles page
2. Next to a role, click on the dropbutton and then click on 'Set permissions'

Expected result
Permissions page is loaded filtered to just that role

Actual result
Permissions page is loaded with previous filters intact

Note
The cause of this is the shift from numeric role ids under Drupal 7 to machine name role ids under Backdrop. The old code is looking for numeric at the end but that won't work.