Random modifications that slightly improve the chances of this not blowing up.

Walter will fix it for real.

Lib/encodings/idna.py

@@ -87,7 +87,7 @@ def ToASCII(label):
         raise UnicodeError("label empty or too long")
 
     # Step 5: Check ACE prefix
-    if label.startswith(uace_prefix):
+    if label.startswith(ace_prefix):
         raise UnicodeError("Label starts with ACE prefix")
 
     # Step 6: Encode with PUNYCODE
@@ -103,7 +103,7 @@ def ToASCII(label):
 
 def ToUnicode(label):
     # Step 1: Check for ASCII
-    if isinstance(label, str):
+    if isinstance(label, bytes):
         pure_ascii = True
     else:
         try:
@@ -150,19 +150,19 @@ class Codec(codecs.Codec):
             raise UnicodeError("unsupported error handling "+errors)
 
         if not input:
-            return "", 0
+            return b"", 0
 
         result = []
         labels = dots.split(input)
         if labels and len(labels[-1])==0:
-            trailing_dot = '.'
+            trailing_dot = b'.'
             del labels[-1]
         else:
-            trailing_dot = ''
+            trailing_dot = b''
         for label in labels:
             result.append(ToASCII(label))
         # Join with U+002E
-        return ".".join(result)+trailing_dot, len(input)
+        return b".".join(result)+trailing_dot, len(input)
 
     def decode(self,input,errors='strict'):
 
@@ -173,13 +173,12 @@ class Codec(codecs.Codec):
             return "", 0
 
         # IDNA allows decoding to operate on Unicode strings, too.
-        if isinstance(input, str):
+        if isinstance(input, bytes):
             labels = dots.split(input)
         else:
-            # Must be ASCII string
-            input = str(input)
-            str(input, "ascii")
-            labels = input.split(".")
+            # Force to bytes
+            input = bytes(input)
+            labels = input.split(b".")
 
         if labels and len(labels[-1]) == 0:
             trailing_dot = '.'