[issue40214] test_ctypes.test_load_dll_with_flags Windows failure

[Kyle Stanley]

New submission from Kyle Stanley <aeros167 at gmail.com>:

In several recent PRs, test_ctypes.test_load_dll_with_flags is failing for the Azure Pipelines "Windows PR tests win32" and "Windows PR tests win64" with the following error message:

```
======================================================================
ERROR: test_load_dll_with_flags (ctypes.test.test_loading.LoaderTest) [WinDLL('_sqlite3.dll', winmode=0)]
----------------------------------------------------------------------
Traceback (most recent call last):
  File "d:\a\1\s\lib\ctypes\test\test_loading.py", line 140, in should_pass
    subprocess.check_output(
  File "d:\a\1\s\lib\subprocess.py", line 419, in check_output
    return run(*popenargs, stdout=PIPE, timeout=timeout, check=True,
  File "d:\a\1\s\lib\subprocess.py", line 533, in run
    raise CalledProcessError(retcode, process.args,
subprocess.CalledProcessError: Command '['d:\\a\\1\\s\\PCbuild\\win32\\python.exe', '-c', "from ctypes import *; import nt;WinDLL('_sqlite3.dll', winmode=0)"]' returned non-zero exit status 1.

======================================================================
ERROR: test_load_dll_with_flags (ctypes.test.test_loading.LoaderTest) [WinDLL('_sqlite3.dll', winmode=0)]
----------------------------------------------------------------------
Traceback (most recent call last):
  File "d:\a\1\s\lib\ctypes\test\test_loading.py", line 140, in should_pass
    subprocess.check_output(
  File "d:\a\1\s\lib\subprocess.py", line 419, in check_output
    return run(*popenargs, stdout=PIPE, timeout=timeout, check=True,
  File "d:\a\1\s\lib\subprocess.py", line 533, in run
    raise CalledProcessError(retcode, process.args,
subprocess.CalledProcessError: Command '['d:\\a\\1\\s\\PCbuild\\win32\\python.exe', '-c', "from ctypes import *; import nt;WinDLL('_sqlite3.dll', winmode=0)"]' returned non-zero exit status 1.
```

Since this only started occurring recently in several unrelated PRs, I suspect it was most likely an intermittent regression introduced in master. Here are the PRs I have seen the same exact error occur in so far:

https://github.com/python/cpython/pull/18239
https://github.com/python/cpython/pull/19403
https://github.com/python/cpython/pull/19402
https://github.com/python/cpython/pull/19399

I was unable to reproduce it locally on my secondary boot of Windows 10.

----------
components: Library (Lib)
keywords: 3.9regression
messages: 365887
nosy: aeros
priority: normal
severity: normal
status: open
title: test_ctypes.test_load_dll_with_flags Windows failure
versions: Python 3.9

_______________________________________
Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue40214>
_______________________________________