Making bit-by-bit reproducible Git Bundles?

Hi.

Thank you for the "git-archive" and "git-bundle" features, making it easier to do source-based builds in a no-Internet environment.

I have published a Git bundle of Gnulib:

https://www.gnu.org/software/gnulib/manual/html_node/Gnulib-Git-Bundle.html

As you can see at the end, I struggle to come up with a recipe to allow others to reproduce the git bundle that I created.

If I run the recipe above twice (including the clone), I get different checksums. This even if nothing was committed in the remote repository meanwhile.

Is it possible to create a bit-by-bit reproducible git bundle using some other set of commands? If so, how? I'm using git 2.48.1 from Guix.

Can anyone explain what is causing the irreproducibility? Running diffoscope is not helpful, since the bundle is compressed and diffoscope doesn't seem to know how to untangle it.

If this is not possible today, what do you think about changes to make this work?

Thanks, /Simon