Migrated site not deleted in platforms sites directory

When migrating a site to the same platform (i.e. renaming the site), everything works fine but the platforms/my_platform/sites directory ends up with both copies of the site (the old one and the renamed one).

Is this normal behaviour? The only way I can safely rename a site right now is by cloning it then deleting the original instance, which correctly deletes the directory in platforms/*/sites.

Also, is it safe to simply delete the site's node on hostmaster + deleting the old directory in sites/ ?