svn_buildbot.py doesn't work with Python3, fails with twistd error

[jdpipe]

The svn_buildbot.py script is rather out of date and doesn't work at all with Python 3. After converting to Python 3 using 2to3, I got it running but then ran into puzzling errors relating to unicode encoding in the communication between the script and the buildbot server...

root@xxx:/srv/[...]# ./svn_buildbot.py -v 3104 -r /srv/[...]
Repo: /srv/[...]
CHANGES [{'revision': b'3104', 'comments': b'creating new branch blah using r3080.\n', 'who': b'user', 'branch': None, 'files': [b'branches/mike/'], 'src': b'svn', 'project': b'', 'repository': b'/srv/[...]'}]
SENDING CHANGES
FAILURE
[Failure instance: Traceback: <class 'TypeError'>: Unicode-objects must be encoded before hashing
/usr/local/lib/python3.4/dist-packages/twisted/spread/pb.py:621:expressionReceived
/usr/local/lib/python3.4/dist-packages/twisted/spread/pb.py:1105:proto_answer
/usr/local/lib/python3.4/dist-packages/twisted/internet/defer.py:459:callback
/usr/local/lib/python3.4/dist-packages/twisted/internet/defer.py:567:_startRunCallbacks
--- <exception caught here> ---
/usr/local/lib/python3.4/dist-packages/twisted/internet/defer.py:653:_runCallbacks
/usr/local/lib/python3.4/dist-packages/twisted/spread/pb.py:1387:_cbResponse
/usr/local/lib/python3.4/dist-packages/twisted/spread/pb.py:1257:respond
]

[jdpipe]

See #6