importlib.metadata.files() doesn't work because RECORD is missing

It appears that `importlib.metadata.files()` is broken with the pypi integration because the RECORD file gets ommited.

Per docs at https://docs.python.org/3/library/importlib.metadata.html#distribution-files

> In the case where the metadata file listing files (RECORD or SOURCES.txt) is missing, files() will return

This came to my attention via @mering trying to use the rtree package, which tries to use its distribution metadata to find some C libraries to load.

Excluding RECORD seems somewhat intentional, though? The code has this comment:

https://github.com/bazel-contrib/rules_python/blob/main/python/private/pypi/whl_library_targets.bzl#L315-L318

> RECORD is known to contain sha256 checksums of files which might include the checksums
> of generated files produced when wheels are installed. The file is ignored to avoid
> Bazel caching issues.

What's the caching issue, exactly? For a downloaded whl, what generated files is it referring to? If a whl is built at repo time from an sdist, then files shouldn't be changing, and the hash should be stable, so how does a cache issue come up?

先从 python/private/pypi/whl_library_targets.bzl 中约第 315-318 行附近关于省略 RECORD 的注释开始，然后将其与 importlib.metadata.files() 文档以及此处描述的 rtree 使用场景进行比较。确定缓存方面的问题，以及 PyPI 集成是否应保留 RECORD 以使 files() 正常工作；当行为和解决方案已记录下来，或已通过验证实现时，即视为完成。

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