NumPy 2.0.0rc1 currently ships OpenBLAS 0.3.26 that has a thread-safety bug on Windows:

• Dead-lock on 0.3.26 on Windows in OpenBLAS multi-threading nested within OpenMP multi-threading OpenMathLib/OpenBLAS#4582

This was fixed in OpenBLAS 0.3.27 but is not yet packaged on pypi.org:

• https://pypi.org/project/scipy-openblas64/

This bug is causing the scikit-learn release CI to freeze when testing against numpy 2.0.0rc1.