Fix dynamic module symlinked cache on trust_remote_code models

[ldkhang1201]

What this fixes

#46617
Loading a trust_remote_code model from a local, symlinked cache crashes with:

FileNotFoundError: [Errno 2] No such file or directory:
'.../blobs/transformers_4_44_2__modeling_rope_utils.py'

A standard huggingface_hub cache stores each file twice:

models--org--repo/
  blobs/<sha>                  # real content, content-addressed, hash-named, no .py extension
  snapshots/<rev>/modeling.py  # symlink -> ../../blobs/<sha>

read: https://huggingface.co/docs/huggingface_hub/en/guides/manage-cache

_compute_local_source_files_hash did Path(resolved_module_file).resolve() before calling
get_relative_import_files. That follows the snapshot symlink into blobs/, and
get_relative_import_files then derives sibling import paths from Path(module_file).parent
(now blobs/). The named .py siblings only exist in snapshots/<rev>/, not in blobs/, so the
lookup raises FileNotFoundError.

Fix

• Run relative-import discovery on the unresolved snapshot path, so traversal stays inside
  snapshots/<rev>/ where the named *.py symlinks live.
• When building the hash key, canonicalize only the parent directory (to normalize symlinked
  path components such as macOS /var→/private/var) and keep the file's logical name.
  read_bytes() still follows the symlink, so content is hashed correctly. For plain
  non-symlinked local dirs the produced hash is unchanged (no cache churn).

Tests

Added a regression test in tests/utils/test_dynamic_module_utils.py that build the real
blobs/ + snapshots/ symlink layout:

• test_get_cached_module_file_local_handles_symlinked_hub_cache — loads a module with a transitive
  relative-import chain (A→B→C) from a symlinked cache; fails on main with the exact
  FileNotFoundError, passes with the fix, and asserts the transitive deps are copied with correct
  content.

$ python -m pytest tests/utils/test_dynamic_module_utils.py -q
16 passed

[Rocketknight1]

Yes, this looks like it makes sense for symlinked remote code dirs!

[HuggingFaceDocBuilderDev]

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[ldkhang1201]

@Rocketknight1 Hi, could you help me merge the PR. I see auto merge is enable but look like the check pr-ci / PR CI status pending is blocking the merge. How could i unblock that ?

[Rocketknight1]

Working on it!

[ldkhang1201]

The check is failing because the test: tests/models/kosmos2_5/test_modeling_kosmos2_5.py::Kosmos2_5ModelTest::test_generate_with_cache_matches_no_cache which passed on my machine and in previous runs. @Rocketknight1 glad if you can help, or give me some resources to working on the problem

[Rocketknight1]

This is just our CI, I'll try rebasing/retrying.

[github-actions]

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[github-actions]

View the CircleCI Test Summary for this PR:

https://huggingface.co/spaces/transformers-community/circle-ci-viz?pr=46618&sha=50b9e4

[ldkhang1201]

This is just our CI, I'll try rebasing/retrying.

Tysm for your work.