Is it deliberate that inner import errors should be treated as if the codec is missing? Another search function isn't going to help in that case unless it finds the same encoding in another place. I didn't see any evidence of that, and apparently neither did Eric (but I was bitten by a misspelt import within my new encodings/oem.py giving a confusing message).

I don't think any encoding modules in the stdlib should fail to import. This change ensures that we hear about it if they do fail.