Custom Block contextual link

Description of the need

I have a custom block on the homepage with intro text that I want the client to be able to edit. So I gave them permission to 'Use contextual links' and 'Administer custom blocks'. However when they hover over the homepage block, no contextual link appears. It seems that you need the 'Administer Layouts' permission to see/use that, but I didn't/don't want to give them that permission. So they can still edit the block using the admin bar, but it'd be nice if they could use the contextual link too.

Proposed solution

It'd be nice if the contextual link was displayed and changed to go to /admin/structure/block/manage/[BLOCK]/configure instead of the Layouts UI if they don't have that permission.