hgfixes: added a fixer to convert changes in the email package This patch adds a fixer that accounts for changes in python packages, as the framework provided by lib2to3 is only able to track changes in module names. This fixer (hopefully) can fix any change in one-level hierarchies. To exemplify, this fixer can successfully change an import from "email.MIMEMultipart" to "email.mime.multipart".