[CI] Docs build cannot fetch cuDF and RMM 26.10 inventories #8557

Summary

Failing test/component: docs-build / build (ci/build_docs.sh)

The Sphinx documentation build emits two intersphinx warnings and exits with status 1 because warnings are treated as errors. The failure occurs in both a push build and a subsequent manually dispatched build of commit 7035f8e3de0f5b9491797f9004d594eaec8cd9a1.

Failure observed in:

• https://github.com/NVIDIA/cuml/actions/runs/33799641187
• https://github.com/NVIDIA/cuml/actions/runs/33799641187/job/100800149057
• https://github.com/NVIDIA/cuml/actions/runs/33845000843
• https://github.com/NVIDIA/cuml/actions/runs/33845000843/job/100937071983

Environment

• OS: Ubuntu 26.04.1, amd64 (rapidsai/ci-conda:26.10-latest)
• Python version: 3.14.7
• CUDA version: 13.3.0
• GPU: L4 runner
• Dependencies: cuML 26.10 docs environment, Sphinx 9.1.0

Test details

• Test file: ci/build_docs.sh

• Test name: sphinx-build -b dirhtml ./source _html -W

• Error message:

  WARNING: failed to reach any of the inventories with the following issues:
  intersphinx inventory 'https://docs.nvidia.com/cudf/26.10/objects.inv' not fetchable due to <class 'requests.exceptions.HTTPError'>: 404 Client Error: Not Found
  WARNING: failed to reach any of the inventories with the following issues:
  intersphinx inventory 'https://docs.nvidia.com/rmm/26.10/objects.inv' not fetchable due to <class 'requests.exceptions.HTTPError'>: 404 Client Error: Not Found
  build finished with problems, 2 warnings (with warnings treated as errors).
  Process completed with exit code 1.
  

The same two warnings occur in both jobs. Related PR: #8549.

Root cause analysis