Given the time frame, how about we just go with Serhiy's suggestion of a "known non-Unicode codec" internal blacklist for both 3.3 and 3.4?

I still like the idea of exposing codec type maps for introspection, but designing a decent API for that which also handles type preserving codecs is going to take some work, and can't realistically be included in 3.4.

By my count, if we delay the blacklisting until after we do the codec lookup, there's only seven names we need to block:

>>> from codecs import lookup
>>> blacklist = "base64 uu quopri hex bz2 zlib rot13".split()
>>> for name in blacklist:
...     print(lookup(name).name)
... 
base64
uu
quopri
hex
bz2
zlib
rot-13