Fix metadata path leaking outside cache when an ancestor dir contains '.py'

[Kymi808]

Summary

_copy_script_and_other_resources_in_importable_dir (src/evaluate/loading.py:333) derives the cache metadata JSON sibling of the loaded script:

meta_path = importable_local_file.split(".py")[0] + ".json"

The intent (per the comment two lines below — *"the filename is .py in our case, so better rename to filenam.json instead of filename.py.json") is to swap the trailing .py extension for .json. But str.split(".py") splits on every occurrence of .py and [0] keeps everything before the first.

For any user whose cache path has .py somewhere in an ancestor directory — .pyenv, .pycache, pypy install paths, project directories containing .py — the prefix gets truncated to before that directory.

A pyenv user with an importable file at
/home/u/.pyenv/versions/.../evaluate_modules/metrics/accuracy/<hash>/accuracy.py
ends up writing the metadata to /home/u/.json — outside the cache tree — and every subsequent evaluate.load(...) clobbers it.

>>> "/home/u/.pyenv/.../accuracy.py".split(".py")[0] + ".json"
'/home/u/.json'                                                # current

>>> os.path.splitext("/home/u/.pyenv/.../accuracy.py")[0] + ".json"
'/home/u/.pyenv/.../accuracy.json'                             # fixed

Fix

Use os.path.splitext(...)[0] so only the trailing extension is stripped, matching the comment's stated intent.

Why this isn't a behavior change someone is relying on

grep -rn '"original file path"\|"local file path"\|meta_path' shows nothing in the repo reads the metadata back — it's write-only informational JSON. The only effect of the bug is junk JSON files at unexpected paths.

Test plan

Added test_copy_script_metadata_path_when_ancestor_dir_contains_py in tests/test_load.py. It calls _copy_script_and_other_resources_in_importable_dir with importable_directory_path = <tmp>/.pyenv/evaluate_modules and asserts:

• the metadata file exists at <tmp>/.pyenv/evaluate_modules/<hash>/accuracy.json (next to the script);
• nothing was leaked to <tmp>/.json.

The test fails on main with AssertionError: meta file missing at <expected path> and passes with this change. pytest tests/test_load.py::test_copy_script_metadata_path_when_ancestor_dir_contains_py → 1 passed.