[Bug 54228] New: CPython fails to import symlinked packages

[WineHQ Bugzilla]

https://bugs.winehq.org/show_bug.cgi?id=54228

Bug ID: 54228
           Summary: CPython fails to import symlinked packages
           Product: Wine-staging
           Version: 8.0-rc2
          Hardware: x86-64
                OS: Linux
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: -unknown
          Assignee: [e-mail]
          Reporter: [e-mail]
                CC: [e-mail], [e-mail]
      Distribution: ---

Created attachment 73774
  --> https://bugs.winehq.org/attachment.cgi?id=73774
complete, minimal reproducing example

- Present in, at least: Wine Staging 7.22 and 8.0-rc2
- Not present: Wine Stable 7.0
- Wine builds: dl.winehq.org/wine-builds/ubuntu
- System: Ubuntu 22.04
- Expected behavior: CPython <= 3.9 can import symlink-ed modules and their
submodules
- Actual behavior: CPython sees the folder and can navigate it, but fails to
import its contents (submodules)
- Reproduced by: https://gist.github.com/s-m-e/84d5fbf5663825a46d9ae98e4636d8ec
(also attached)

---

I have noticed this issue in Wine Staging 7.22 and 8.0-rc2. I believe it must
have found its way into Wine Staging in the October to November 2022 time
frame. This issue does not appear in Wine Staging until about September. It
also does not appear in stable releases of Wine 7. Python's import mechanism
was rewritten recently, so only versions prior to Python 3.10 appear to be
affected. Many packages support down to 3.7 at the moment.

I am heavily using CPython on top of Wine. When Python imports modules, it
looks for them in certain paths, specified in `sys.path`. For development, it
is common practise to symlink a package's folder from e.g. a git repo into one
of the folders contained in `sys.path`, usually `site-packages`. Python then
happily imports the module from there for e.g. testing. Many tools are built
around this workflow.

```
Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "Z:\work\bar__init__.py", line 1, in <module>
    from .subbar import funcbar
ModuleNotFoundError: No module named 'bar.subbar'
```

Python's module import mechanism appears to follow the symlink correctly (into
module "bar") but fails to "locate" stuff within the linked folder (submodule
"bar.subbar"). Other Python code can at least correctly navigate the linked
folder's contents, so I am suspecting a `stat` syscall of some kind to return
unusual values.

For a complete, minimal reproducing example see link above or attached script.