preppy recipe build fail

### Logs

```
[INFO]: Downloading preppy from https://bitbucket.org/rptlab/preppy/get/27b7085.tar.gz
Traceback (most recent call last):
File "/usr/lib/python3.10/runpy.py", line 196, in _run_module_as_main
return _run_code(code, main_globals, None,
File "/usr/lib/python3.10/runpy.py", line 86, in _run_code
exec(code, run_globals)
File "/home/bobf/ex/regression/.buildozer/android/platform/python-for-android/pythonforandroid/toolchain.py", line 1312, in
main()
File "/home/bobf/ex/regression/.buildozer/android/platform/python-for-android/pythonforandroid/entrypoints.py", line 18, in main
ToolchainCL()
File "/home/bobf/ex/regression/.buildozer/android/platform/python-for-android/pythonforandroid/toolchain.py", line 734, in __init__
getattr(self, command)(args)
File "/home/bobf/ex/regression/.buildozer/android/platform/python-for-android/pythonforandroid/toolchain.py", line 153, in wrapper_func
build_dist_from_args(ctx, dist, args)
File "/home/bobf/ex/regression/.buildozer/android/platform/python-for-android/pythonforandroid/toolchain.py", line 212, in build_dist_from_args
build_recipes(build_order, python_modules, ctx,
File "/home/bobf/ex/regression/.buildozer/android/platform/python-for-android/pythonforandroid/build.py", line 482, in build_recipes
recipe.download_if_necessary()
File "/home/bobf/ex/regression/.buildozer/android/platform/python-for-android/pythonforandroid/recipe.py", line 348, in download_if_necessary
self.download()
File "/home/bobf/ex/regression/.buildozer/android/platform/python-for-android/pythonforandroid/recipe.py", line 398, in download
self.download_file(self.versioned_url, filename)
File "/home/bobf/ex/regression/.buildozer/android/platform/python-for-android/pythonforandroid/recipe.py", line 202, in download_file
urlretrieve(url, target, report_hook)
File "/usr/lib/python3.10/urllib/request.py", line 241, in urlretrieve
with contextlib.closing(urlopen(url, data)) as fp:
File "/usr/lib/python3.10/urllib/request.py", line 216, in urlopen
return opener.open(url, data, timeout)
File "/usr/lib/python3.10/urllib/request.py", line 525, in open
response = meth(req, response)
File "/usr/lib/python3.10/urllib/request.py", line 634, in http_response
response = self.parent.error(
File "/usr/lib/python3.10/urllib/request.py", line 563, in error
return self._call_chain(*args)
File "/usr/lib/python3.10/urllib/request.py", line 496, in _call_chain
result = func(*args)
File "/usr/lib/python3.10/urllib/request.py", line 643, in http_error_default
raise HTTPError(req.full_url, code, msg, hdrs, fp)
urllib.error.HTTPError: HTTP Error 404: Not Found
```

Start with pythonforandroid/build.py, pythonforandroid/recipe.py, and the recipe entry point involved in downloading preppy. Reproduce the build to confirm the HTTP 404, then trace how the recipe's versioned URL is selected. Done means the preppy recipe downloads successfully and the relevant build path completes without this error.

索引モデルが issue の本文から書いたものです。