In wheel we had to jump through some hoops to do rfc822 style documents with utf-8, a task which can also be accomplished more easily with newer versions of the standard Python 3 email library (but not the versions we had to support at the time). https://bitbucket.org/pypa/wheel/src/1cb7374c9ea4d5c82992f1d9b24cf7168ca87707/wheel/pkginfo.py?at=default&fileviewer=file-view-default