> Probably os.execv() should be implemented on Windows with _wexecv() instead
> of _execv(). 

That's a different story. Would you like to implement it? If yes, please open a 
new issue.

> I don't know what you mean about os.readlink() though: the Windows
> implementation uses CreateFileW() and DeviceIoControl().

Oops, you are right. The Windows implement only accepts Unicode, so no 
deprecation warning is needed here.