Python bug in Windows 8--report now, or later?

[Kevin Walzer]

I have been testing my Python application on the just-released developer 
preview of Windows 8 and have noted an error: the application does not 
create an app folder in the user's "application data" directory. This 
causes the app to crash on startup. Manually creating the directory 
solves the problem. Since the app uses an os.mkdir() call to create the 
directory, and since the app runs fine on Windows 7, my guess is that 
the bug lies somewhere in the interaction between Python (I'm using 
ActivePython 2.7) and Windows.

Here's the relevant code:

     #make preferences directory if it does not exist
     def makePrefsDir(self):
         self.appdir = os.path.join(os.path.join(os.environ['APPDATA'], 
'MyApp'))
         if not os.path.exists(self.appdir):
             os.mkdir(self.appdir)

I realize that this developer preview of Windows is still at somewhere 
between alpha- and beta-level, and it's possible things will get better. 
Should I wait to report this as a bug until Windows 8 is released, or do 
the Python developers test Python on pre-release versions of Windows?