python2.6's sys.version_info isn't a namedtuple.

dkimverify.py

@@ -27,7 +27,7 @@ import sys
 
 import dkim
 
-if sys.version_info.major >= 3:
+if sys.version_info[0] >= 3:
     # Make sys.stdin a binary stream.
     sys.stdin = sys.stdin.detach()