Build failure: python311Packages.curio (impurity issue?)

[Qyriad]

Steps To Reproduce

Steps to reproduce the behavior:

1. nix build 'github:NixOS/nixpkgs/master#python311Packages.curio' --rebuild
2. Observe that the test tests/test_workers.py::test_cpu fails

Note the --rebuild, as this package is successfully building in Hydra, so I can only assume this is an impurity or non-determinism issue.

Build log

https://gist.github.com/Qyriad/f2387d0fd7ebb61f5270dc6a3d3b544d

Additional context

• I reproduced this on Nixpkgs commit 68ead29.
• python312Packages.curio and python310Packages.curio both succeed without issue

Notify maintainers

@pbsds

Metadata

 - system: `"x86_64-linux"`
 - host os: `Linux 6.6.30, NixOS, 24.05 (Uakari), 24.05.20240517.4a6b83b`
 - multi-user?: `yes`
 - sandbox: `yes`
 - version: `nix-env (Lix, like Nix) 2.90.0-lixpre20240518-62b1adf
 - nixpkgs: `/nix/store/0aavdx9m5ms1cj5pb1dx0brbrbigy8ij-source`

(Note: it says "Lix" as that's the primary Nix on my system, but I also reproduced this with Nix 2.18 with sudo nix run 'nixpkgs#nixVersions.nix_2_18' -- build 'github:NixOS/nixpkgs/master#python311Packages.curio' --rebuild --store local, so this is certainly not a Lix-specific issue)

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[Qyriad]

Build for python39Packages.curio just finished successfully, so this is just failing on 3.11

[pbsds]

Thank you. I was unable to reproduce even while running stress, but the provided log proved a race condition i found while reading the test. Fixed in #312874