XZise added a comment.
I'll take a closer look at this later but it seems that we should encode all header entries to ASCII before we are sending it away. I guess in Python 3 httplib2 is doing that for us.
TASK DETAIL https://phabricator.wikimedia.org/T99366
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To: zhuyifei1999, XZise Cc: valhallasw, XZise, Aklapper, zhuyifei1999, jayvdb, pywikipedia-bugs