`nix copy` does not preserve provenance

[andre4ik3]

Describe the bug

nix copy does not preserve provenance information.

Steps To Reproduce

(assuming both machines have provenance feature enabled)

1. On machine A, nix build --option substitute false nixpkgs#hello
2. On machine A, observe that nix provenance show reports provenance information
3. On machine B, nix copy --from ssh-ng://machine-a /nix/store/...-hello --no-check-sigs
4. On machine B, observe that nix provenance show says "no provenance information available"

Expected behavior

nix copy preserves provenance information, and running nix provenance show on machine B should report the same provenance as on machine A, plus also the fact that it was copied from machine B.

Metadata

Nix (Determinate Nix 3.16.2) 2.33.3

Additional context

Checklist

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