It's relatively easy to replace mimetools in most places: it's just a 
matter of changing mimetools.Message to email.message_from_file, but it 
gets a lot more complicated when there's inheritance involved.

The problem is that mimetools.Message is both a parser and a Message 
representation, and AFAIK there's no single class in ``email`` which does 
both -- the functionality is split between the Parser and Message classes.

Inheritance happens in two places: ``pydoc.Message`` and 
``http.client.HTTPMessage``, and I couldn't find a solution for those 
cases yet. Any help would be appreciated.