OK so There was a change made to fix issue 26628. Something was forgotten about.. On Windows there is the VARIANT Union which gets used all over the Windows API. This change is going to really break a lot of peoples code and there are no code examples of what needs to be done to fix the now broken ctypes, what needs to be done instead of passing a Union? what new structure has been made that Windows is going to se as a Union? 
That is a huge change to make with no kind of notice that it was going to be done. Now I know it is publicly visible on your issue tracker, but come on now the issue was made 4 years ago and then all of a sudden out of no where boom broken software.. Now If that issue was a major issue and it was causing all kinds of grief I would think that it 
A. would have been fixed sooner... and 
B. there would have been more then a handful of people where the original "bug" caused a problem. 

I am wondering if maybe this bug is a NIX issue. there are simply way to many programs out that are running on Windows and Unions are being passed all the time in functions and no problems are occurring. If there were problems with it in Windows you would have 1000's of reports of crashing from this problem. 

A change like that should be posted on the Python website before it gets made so that all possible repercussions can be looked at.