Mark 2to3 as compatible with python-2.5 per the discussion in issue 8566.

pep-0291.txt

@@ -82,16 +82,19 @@ Features to Avoid
 
           2.4      with statement, conditional expressions,
                    combined try/except/finally, relative imports,
-                   yield expressions or generator.throw/send/close()
+                   yield expressions or generator.throw/send/close(),
+                   plus all features below
 
-          2.5      ???
+          2.5      with statement without from __future__ import,
+                   io module, str.format(), except as,
+                   bytes, b'' literals, property.setter/deleter
 
 
 Backward Compatible Packages, Modules, and Tools
 
     Package/Module     Maintainer(s)          Python Version     Notes
     --------------     -------------          --------------     -----
-    2to3               Benjamin Peterson           2.6
+    2to3               Benjamin Peterson           2.5
     bsddb              Greg Smith                  2.1
                        Barry Warsaw
     compiler           Jeremy Hylton               2.1