[IronPython] _WindowsError and errno

[Jeff Hardy]

Hi IronPython team,
Is there any reason why _WindowsError sets errno to 22 in all cases?
There's some code in Django that checks if e.errno = errno.EEXIST. The
exception that gets thrown by IronPython has winerror = 17 (and the
message string says "[Errno 17]..."!), but e.errno is 22 (EINVAL).

Fixing #19310 would avoid the problem in this case (it's the same
chunk of code), but I'm curious in general what the reason is.

- Jeff