> I would still like to see the zipfile module to be able to detect 
> ill-formed zipfiles - certainly not by default.

Agreed.  We already do produce some informational messages via the 
documented 'ZipFile.debug' attribute.  Just checking that flag and
producing a message to stdout like we do in other cases is one option.
Another, as you suggested already, is to provide a strict flag
that indicates an exception should be thrown upon encountering an 
ill-formed file.

I like the idea of reusing what we already have.  Although, when it 
fails, it doesn't fail loudly.