request_uri isn't quite the same as Apache's DOCUMENT_NAME, and it'll bite you eventually:
DOCUMENT_NAME (Apache) = just the filename, no path, no query string. e.g. index.shtml
$request_uri (nginx) = the full original URI including query string, e.g. /blog/post.html?utm_source=feed
So it'll work fine until something hits a URL with a ?... on it, or you reuse the include somewhere nested and want just the filename, not the whole path.
If you want a true filename-only equivalent, nginx doesn't expose one natively, but you can derive it with a map: