Revert hotfix CI for TypeError: 'NoneType' object is not iterable

[albertvillanova]

Revert hotfix CI for TypeError: 'NoneType' object is not iterable

This reverts commit d3a7fca:

• Hotfix CI: Mark tests as xfail with transformers dev due to TypeError: 'NoneType' object is not iterable #5427

Note that my upstream fix in transformers is already merged:

• Fix TypeError: 'NoneType' object is not iterable in GenerationMixin.generate transformers#45164

This PR removes an xfail marker for the "trl-internal-testing/tiny-LlavaNextForConditionalGeneration" model in two test files. This means the related tests will no longer be expected to fail due to the previously referenced upstream issue.

Changes

Test suite updates:

• Removed the pytest.mark.xfail marker for "trl-internal-testing/tiny-LlavaNextForConditionalGeneration" in test_prepare_input_called_with_correct_data in both tests/test_grpo_trainer.py and tests/test_rloo_trainer.py, so these tests will now run as normal.

---

Note

Low Risk
Only adjusts pytest expectations by removing an xfail guard, so risk is limited to potentially reintroducing CI failures if the upstream transformers regression resurfaces.

Overview
Removes the conditional pytest.mark.xfail around the trl-internal-testing/tiny-LlavaNextForConditionalGeneration VLM case in both tests/test_grpo_trainer.py and tests/test_rloo_trainer.py, so these parametrized vision-language trainer tests now run and are expected to pass on dev transformers versions as well.

^{Written by Cursor Bugbot for commit 8b1f6c4. This will update automatically on new commits. Configure here.}

[HuggingFaceDocBuilderDev]

The docs for this PR live here. All of your documentation changes will be reflected on that endpoint. The docs are available until 30 days after the last update.

[qgallouedec]

LGTM if this CI does pass