Any function which is not static to a file, must be prefixed with Py or _Py. There are several lines which are over 80 columns and should be wrapped. Why is errno set in open_utf8, etc?
Indentation was messed up at least in one place in Objects/moduleobject.c on a DECREF line.
I can't provide any guidance on the windows specific code. Where do _wstat and _wfopen come from? There isn't a man page on my Unix box. I'm not sure if the exist in a library anywhere. I didn't see any changes to configure to verify if these exist or not. If Py_UNICODE_IMPORT, does that necessarily mean these APIs exist? (It's possible this code was inside an #if WINDOWS and I couldn't tell from the patch.)