nix flake clone fails on a remote flake with a dir parameter

[LeonChambers]

Describe the bug

Running nix flake clone on a remote flake with a dir parameter fails with

fatal: remote error:
  is not a valid repository name

Steps To Reproduce

nix flake clone git+ssh://[email protected]/NixOS/nix?dir=tests/functional/ca/flake.nix --dest test is a simple way to reproduce it. I actually ran into this running nixos-rebuild switch with my personal github repo, but the error message is the same. If you remove the dir parameter, the command works as expected

Expected behavior

This used to work and successfully clone the repo.

Metadata

nix-env (Nix) 2.24.12

Additional context

I tried bisecting this myself on the 2.24-maintenance branch. It seems like it started failing in 6e44bc2

Checklist

• checked latest Nix manual (source)
• checked open bug issues and pull requests for possible duplicates

---

Add 👍 to issues you find important.

[jsimonetti]

I think this is related to #12438

[n0rad]

It's a pretty big issue to me.

As soon as jumping into >= 2.24.12, devices cannot be updated anymore since nixos-rebuild is broken for flake that are not at the root of the git repository, and devices using nixos-upgrade.service to reconcile will stay in a broken state forever.