fetchTarball regression in nixUnstable?

[colinxs]

Describe the bug

builtins.fetchTarball no longer works if there is more than one top level directory in a tarball.

Steps To Reproduce

Welcome to Nix version 2.4pre20210503_6d2553a. Type :? for help.

nix-repl> builtins.fetchTarball {url="https://pkg.julialang.org/artifact/c91b35452c8fa91e8ac43993a2bc8fb4f78476bb";}
error: tarball 'https://pkg.julialang.org/artifact/c91b35452c8fa91e8ac43993a2bc8fb4f78476bb' contains an unexpected number of top-level files

Welcome to Nix version 2.3.10. Type :? for help.

nix-repl> builtins.fetchTarball {url="https://pkg.julialang.org/artifact/c91b35452c8fa91e8
ac43993a2bc8fb4f78476bb";}
"/nix/store/jwm4hzafk0yy31bysgw51vhknvvgh4an-source"

Expected behavior

A clear and concise description of what you expected to happen.

nix-env --version output

Additional context

Add any other context about the problem here.

[stale[bot]]

I marked this as stale due to inactivity. → More info

[cole-h]

Not stale -- someone just came across this in the Nix / NixOS matrix.

@edolstra: is there a reason why Nix expects only one top-level file in tarballs? This was introduced in https://github.com/NixOS/nix/commit/8918bae09828133259acb36d6aef60ffbfad252c.

[nixos-discourse]

This issue has been mentioned on NixOS Discourse. There might be relevant details there:

https://discourse.nixos.org/t/nix-2-4-and-what-s-next/16257/1

[nixos-discourse]

This issue has been mentioned on NixOS Discourse. There might be relevant details there:

https://discourse.nixos.org/t/nix-2-4-and-what-s-next/16257/8

[stale[bot]]

I marked this as stale due to inactivity. → More info

[yorickvP]

Haven't seen this be fixed

[deliciouslytyped]

Still an issue.

[2xsaiko]

Did this actually ever work? Blame shows it as introduced with https://github.com/NixOS/nix/commit/462421d34588c227eb736b07f7b40a38aa0972a6, and before https://github.com/NixOS/nix/commit/8918bae09828133259acb36d6aef60ffbfad252c.

Related: #7083

[tomberek]

Docs say

The top-level path component of the files in the tarball is removed, so it is best if the tarball contains a single directory at top level. 

which implies a single top-level dir is "best", but it a bit confusing.

needs decision

• [ ] WONT FIX : behavior is as desired
• [ ] BUG: the regression should be resolved

Fixed By: https://github.com/NixOS/nix/pull/9053