[CI][Python] The pandas upstream_devel nightly build is skipping all pandas tests

[jorisvandenbossche]

The test-conda-python-3.11-pandas-upstream_devel is not working correctly, see eg https://github.com/ursacomputing/crossbow/actions/runs/7454906275/job/20283098411. This build is green, but that also partly because it just skipped all pandas related tests (the test-conda-python-3.10-pandas-nightly is working fine, this install pandas from a nightly wheel instead of building it from source).

I assume this is because the import of pandas fails. And the reason this import is failing is probably related to #39532.
My current assumption is that we are building pandas from source, but in the isolated build for that still build with numpy 1.x. But the installed numpy version is the nightly numpy 2.0.0.dev. And then you get an incompatibility (to run with numpy 2.0, pandas also needs to be built against it)

[jorisvandenbossche]

(we still have the pandas-nightly build as well, so the lack of the upstream_devel build shouldn't be a release blocker)

[jorisvandenbossche]

This is fixed nowadays (see eg https://github.com/ursacomputing/crossbow/actions/runs/8682389305/job/23806826378 for the latest build), so closing this issue.

(this might be because pandas will now install numpy latest in its isolated build)