Using tempfile.TemporaryDirectory() in Windows, creating read-only files in this temp directory leads to PermissionError during the cleanup().
This is a direct cause of this one:
https://bugs.python.org/issue19643

And the workaround which was proposed in the issue 19643 and added to the doc here:
https://docs.python.org/3/library/shutil.html?highlight=shutil#rmtree-example

is not used in the TemporaryDirectory implementation.

I don't know if the right solution is to modify the implementation to systematically delete read-only files using the cited workaround, or to add a 'remove_readonly' flag or to update the documentation to clearly says that cleanup will raise a PermissionError if the user creates a read-only file. At least documentation please :)

In my specific usecase I "git clone" in the temp directory, and the .git folder contains read-only files.

Full stacktrace:
Traceback (most recent call last):
  File "C:\mycode.py", line 149, in build_libraries
    update(generated_path, dest_folder)
  File "C:\Program Files\Python35\lib\tempfile.py", line 807, in __exit__
    self.cleanup()
  File "C:\Program Files\Python35\lib\tempfile.py", line 811, in cleanup
    _shutil.rmtree(self.name)
  File "C:\Program Files\Python35\lib\shutil.py", line 488, in rmtree
    return _rmtree_unsafe(path, onerror)
  File "C:\Program Files\Python35\lib\shutil.py", line 378, in _rmtree_unsafe
    _rmtree_unsafe(fullname, onerror)
  File "C:\Program Files\Python35\lib\shutil.py", line 378, in _rmtree_unsafe
    _rmtree_unsafe(fullname, onerror)
  File "C:\Program Files\Python35\lib\shutil.py", line 378, in _rmtree_unsafe
    _rmtree_unsafe(fullname, onerror)
  File "C:\Program Files\Python35\lib\shutil.py", line 378, in _rmtree_unsafe
    _rmtree_unsafe(fullname, onerror)
  File "C:\Program Files\Python35\lib\shutil.py", line 383, in _rmtree_unsafe
    onerror(os.unlink, fullname, sys.exc_info())
  File "C:\Program Files\Python35\lib\shutil.py", line 381, in _rmtree_unsafe
    os.unlink(fullname)
PermissionError: [WinError 5] Access is denied: 'C:\\Users\\me\\AppData\\Local\\Temp\\tmpk62cp34t\\readonly.file'