Describe the bug

$ nix copy --from ~/tmp-store-normal --to ~/tmp-store-hacked?use-case-hack=true /nix/store/6hypxafvp2fcadphppjcxszx0qcahqbz-dummy
warning: unknown setting 'use-case-hack'

I shouldn't have to apply the case hack (unhack) to the --from store.

Steps To Reproduce

See above.

Expected behavior

• The case hack is a store setting.
• Ideally, need for the case hack is autodetected based on the file system where the store resides
  • Darwin does not imply case-insensitive file system #1446

nix-env --version output

Additional context

• Collect "file system object" parts of libnixutil together #9278

  • libnixfile isn't a thing (yet?), but is a useful indictor of the abstraction level: Nix operations on files without the need for an actual store.

• Darwin does not imply case-insensitive file system #1446

Priorities

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