Unsupported transport-layer encodings

When a server sends:

   Content-Type: text/html; charset=unsupported

what should a UA do?

In the spec, "Determining the character encoding" says "If the transport 
layer specifies an encoding, return that encoding with the confidence 
/certain/, and abort these steps." so the encoding has the value 
"unsupported". (Step 7 of that algorithm (which defaults to something 
undefined, typically Windows-1252) is never reached, since step 1 returns.)

Also the spec says "The bytes encode the actual characters according to 
a particular /character encoding/, which the user agent must use to 
decode the bytes into characters.", so it sounds like the UA must decode 
with the "unsupported" encoding, which it can't because it doesn't 
support that. I can't find anything that says to fall back to some other 
(supported) encoding.

-- 
Philip Taylor
pjt47@cam.ac.uk