Convert input to a string object. Fixes #909230.
Backported 2.3.
diff --git a/Lib/encodings/idna.py b/Lib/encodings/idna.py
index 37462db..4814215 100644
--- a/Lib/encodings/idna.py
+++ b/Lib/encodings/idna.py
@@ -171,6 +171,7 @@
             labels = dots.split(input)
         else:
             # Must be ASCII string
+            input = str(input)
             unicode(input, "ascii")
             labels = input.split(".")