I see from this. That this is still an issue
https://github.com/python/cpython/blob/master/Lib/subprocess.py#L1146

Is it not a solution to
save current directory location
chdir(cwd) before calling  _winapi.CreateProcess()
restore the original directory.

This will result in the cwd being searched for the executable, which most people would expect to happen.  It seems CreateProcess does not change to cwd until after the file is checked for existence or loaded.