Files in subdirs in `test-sources` fail to copy into the test cwd on linux

[joerick]

It would be nice, though. It would make local running easier. :) The rename might not be that bad as long as no content changes in renamed files, it might be able to track though it.

This looks like a bug in cibuildwheel (or my understanding of how to specify test-sources):

test-sources = ["tools", "numpy/conftest.py", "pyproject.toml", "pytest.ini"]

Successfully installed numpy-2.3.0.dev0
    + mkdir -p /tmp/tmp.UKbQJ5C2pd/test_cwd
    + mkdir -p /tmp/tmp.UKbQJ5C2pd/test_cwd/tools
sh: /tmp/tmp.UKbQJ5C2pd/test_cwd/numpy/conftest.py: No such file or directory

                                                             ✕ 16.38s
cibuildwheel: error: Command ['docker', 'exec', '-i', 'cibuildwheel-800ebe67-e43e-49be-b232-eee7dc55a646', 'sh', '-c', 'cat > /tmp/tmp.UKbQJ5C2pd/test_cwd/numpy/conftest.py'] failed with code 1.

Originally posted by @henryiii in numpy/numpy#29007 (comment)

[henryiii]

@freakboy3742 Could you take a look, perhaps?

[freakboy3742]

@henryiii I'm currently in transit from PyCon US; will take a look as soon as my brain is no longer mush :-)

[freakboy3742]

I've found the source of the problem - the oci_containers.copy_into() method assumes it can copy a single file, or a directory; but if it's copying a single file, it assumes the path for the single file already exists. As a result, copying numpy/conftest.py fails, because the destination numpy directory doesn't exist. Patch incoming.