[Bugfix] Skip fetching revision for model when model and weights_model are different

[music-dino]

Purpose

After PR #49990, two gguf tests soft failed on the nightly https://buildkite.com/vllm/ci/builds/82629/list?sid=019fd5a9-db3f-42ba-9b21-993c983b2c7d&tab=output

• plugins_tests/gguf/test_gguf_plugin_generate.py::test_models[1-8-32-bfloat16-model0]
• plugins_tests/gguf/test_gguf_plugin_generate.py::test_models[1-8-32-bfloat16-model1]
  with the following error:

(EngineCore pid=4804)   File "/usr/local/lib/python3.12/dist-packages/huggingface_hub/utils/_http.py", line 811, in hf_raise_for_status
(EngineCore pid=4804)     raise _format(RevisionNotFoundError, message, response, repo_type=repo_type, repo_id=repo_id) from e
(EngineCore pid=4804) huggingface_hub.errors.RevisionNotFoundError: 404 Client Error. (Request ID: Root=1-6a7458a2-4c53f152377c40525f02539b;bbb6ea76-c273-4cc6-8a9d-f476cecea6a0)
(EngineCore pid=4804) 
(EngineCore pid=4804) Revision Not Found for url: https://huggingface.co/api/models/unsloth/Qwen3-0.6B-GGUF/tree/c1899de289a04d12100db370d81485cdf75e47ca?recursive=true&expand=false.
(EngineCore pid=4804) Invalid rev id: c1899de289a04d12100db370d81485cdf75e47ca

Root cause

ModelConfig can load config and weights from different repos. The GGUF plugin redirects model to the base repo (Qwen/Qwen3-0.6B) for config while keeping the GGUF weights repo (unsloth/Qwen3-0.6B-GGUF) in model_weights.

Currently revision is resolved against self.model unconditionally

self.revision = resolve_revision(self.model, self.revision, self.hf_token)

Because revision is a single field shared by all repos, this base-repo hash is then handed to snapshot_download for the weights repo. huggingface_hub sees an already-resolved revision, skips re-resolving, and requests the base repo's commit from the weights repo. Previously revision stayed None, so snapshot_download resolved main against the weights repo correctly.

This PR only resolves the shared revision against self.model when the weights actually come from the same repo.

Test Plan

pytest -v -s "plugins_tests/gguf/test_gguf_plugin_generate.py::test_models[1-8-32-bfloat16-model0]" "plugins_tests/gguf/test_gguf_plugin_generate.py::test_models[1-8-32-bfloat16-model1]"

Test Result

Previously both tests failed with the aforementioned error, now they pass

[claude]

Claude Code Review

This pull request is from a fork — automated review is disabled. A repository maintainer can comment @claude review to run a one-time review.

[mergify]

Hi @music-dino, the pre-commit checks have failed. Please run:

uv pip install pre-commit>=4.5.1
pre-commit install
pre-commit run --all-files

Then, commit the changes and push to your branch.

For future commits, pre-commit will run automatically on changed files before each commit.

[hmellor]

/ci run

[hmellor]

/ci run

[github-actions]

✅ Triggered Buildkite CI #82815 for commit 570c18120b34.