Have namedtuple's field renamer assign names that
are consistent with the corresponding tuple index.
diff --git a/Lib/collections.py b/Lib/collections.py
index 002ce97..786a9f7 100644
--- a/Lib/collections.py
+++ b/Lib/collections.py
@@ -174,7 +174,7 @@
             if (not all(c.isalnum() or c=='_' for c in name) or _iskeyword(name)
                 or not name or name[0].isdigit() or name.startswith('_')
                 or name in seen):
-                names[i] = '_%d' % (i+1)
+                names[i] = '_%d' % i
             seen.add(name)
         field_names = tuple(names)
     for name in (typename,) + field_names: