Glob matching an image from a branch bundle below the bundle?

Given this directory structure

.
├── _index.md
├── country.,jpg
├── city1
    ├── img1.jpg
    ├── index.md
└── city2
    ├── img2.jpg
    ├── img3.jpg
    ├── index.md

I want to find img1.jpg from the top level bundle without knowing that it is located in city1.
Using .Resources.GetMatch "**/img1.jpg" in _index.md does not return the image, but
.Resources.GetMatch "*/**/img1.jpg" does

OTOH, .Resources.GetMatch "*/**/country.jpg" does not return country.jpg, whereas .Resources.GetMatch "**/country.jpg" does.

The documentation says that

Super wildcard (**) matches any character including delimiters.

Shouldn’t than **/img1.jpg match ./city1/img1.jpg?

In general, how should one write a glob pattern to match a file either in the current branch bundle or any bundle below it?

Unless you’re using an image render hook that looks through the page resources of descendant pages, none of the resources in the descendant pages should be available to the “top level bundle” (_index.md your tree diagram).

https://gohugo.io/content-management/page-bundles/#comparison

excludes descendant bundles

Thanks. I saw that and wondered if it described what I was seeing.