Exclude frontpage alias automatically?

Problem/Motivation

We've noticed that on our sitemaps, the path `/` (the front page) and also the full alias of the frontpage node are both indexed by default.

Is there a way (or could there be a way) to automatically exclude the real alias of the frontpage so that they are not duplicated in the sitemap?

Steps to reproduce

Create a sitemap on a site where the frontpage is a standard node of a specific bundle or content type.

Proposed resolution

Automatically exclude the alias of the frontpage node (or view or whatever) from being indexed in the sitemap so that the frontpage does not appear twice.

Remaining tasks

User interface changes

API changes

Data model changes