Non-deterministic behavior when rerendering pytensor-suite-feedstock

[maresb]

Solution to issue cannot be found in the documentation.

• I checked the documentation.

Issue

See conda-forge/pytensor-suite-feedstock#54 for technical details of my debugging attempts.

In short, since several months, running conda-smithy rerender randomly skips .ci-support files which shouldn't be skipped. It took me several hours with the debugger to get an idea about what's going on.

To reproduce:

1. Clone conda-forge/pytensor-suite-feedstock
2. Run conda-smithy rerender
3. Run git status and check for deleted files under .ci_support/
4. Repeat, and observe files appearing and disappearing from .ci_support/ at random.

My rough understanding is that conda-smithy calls conda-build in order to determine whether to render a group like osx-arm64. Associated to this group is a set of Python versions ranging from 3.8 to 3.11. The recipe contains skip: true # [py<39]. In evaluating whether or not to skip osx-arm64, a Python version is selected at random. Whenever 3.8 comes up, it skips osx-arm64 and causes the corresponding .ci-support files to go missing.

Installed packages

conda-build 3.25.0, conda-smithy 3.26.2, and conda-forge-pinning 2023.10.07.18.27.00

Environment info

N/A

[mbargull]

Hi @maresb,
the conda-smithy part of this issue is likely fixed via gh-1815 in a future conda-smithy release.
Another part of the issue which makes it much more likely to occur for pytensor-suite-feedstock is due to its usage of the py selector in the top-level skip line of the recipe in combination with python being only used for the outputs.
I've suggested a change to better handle this case in conda-build via conda/conda-build#5139 .
See that pull request's description for more details on why it happens and also how you could work around it for now in the recipe.

[maresb]

Thanks @mbargull for helping me solve #54. That was the functional problem I was trying to solve.

Please feel free to close this issue whenever you see fit. Thanks so much for tracking down these really subtle problems!!!