Don't "fix" things on Python 3 that are already fixed.

src/allmydata/windows/fixups.py

@@ -1,4 +1,6 @@
 from __future__ import print_function
+
+from future.utils import PY3
 from past.builtins import unicode
 
 # This code isn't loadable or sensible except on Windows.  Importers all know
@@ -122,6 +124,10 @@ def initialize():
 
     SetErrorMode(SEM_FAILCRITICALERRORS | SEM_NOOPENFILEERRORBOX)
 
+    if PY3:
+        # The rest of this appears to be Python 2-specific
+        return
+
     original_stderr = sys.stderr
 
     # If any exception occurs in this code, we'll probably try to print it on stderr,