Description of problem: The py3 eventlent may have trouble supporting the hooks we put in for the 100-continue tag-along headers. So, should switch over to a simpler HTTP protocol (an implementation is available for review upstream).
Althought the feature is implemented (see the linked upstream Gerrit), the upstream team found a way to live without it. We talked the developers of eventlet into accepting certain patches that permit us live on py3 as we did on py2. Closing as wontfix for now. We can always re-open if necessary.