Mysterious conflict hint involving __cuda

[leofang]

Moving part of the discussion from #9115.

Observation made by @jjhelmus:

conda includes __cuda in the conflict hints for non-obvious reason. I've seen this occasionally, I do not think __cuda is the source of the conflict but the hinting algorithms reports it for some reason.

Original report:

When testing nsls-ii-forge/cupy-feedstock#1, I noticed that __cuda imposed addition constraint on the allowed NumPy version (or the other way around).

See e.g. an error log from our CI when I tried to specify the scipy version:
https://dev.azure.com/nsls2forge/nsls2forge/_build/results?buildId=2457&view=logs&j=d0d954b5-f111-5dc4-4d76-03b6c9d0cf7e&t=6d4b912b-175d-51da-0fd9-4d30fe1eb4e7&l=609

...

Package numpy conflicts for:
scipy[version='>=1.0,<1.1'] -> numpy[version='>=1.9|>=1.9.3,<2.0a0']
numpy[version='>=1.9.0']

Package libgomp conflicts for:
libgcc-ng[version='>=7.3.0'] -> _openmp_mutex[version='>=4.5'] -> libgomp[version='>=7.3.0']
gcc_linux-64 -> gcc_impl_linux-64=7.3.0 -> libgomp[version='>=7.3.0']The following > specifications were found to be incompatible with your CUDA driver:

 - feature:/linux-64::__cuda==10.2=0
 - feature:|@/linux-64::__cuda==10.2=0

Your installed CUDA driver is: 10.2
...

By the way, the CI would be happy if I remove >=1.0,<1.1 for scipy.

[jakirkham]

(subscribed 😉)

[github-actions]

Hi there, thank you for your contribution!

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Thanks!

[jakirkham]

Let's keep this one open please