UnicodeError: source returned bytes, but no encoding specified

[porqpynz@…]

How to Reproduce

While doing a GET operation on /roadmap, Trac issued an internal error.

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_10_5) AppleWebKit/601.2.7 (KHTML, like Gecko) Version/9.0.1 Safari/601.2.7

System Information

Trac	1.0.2
Babel	1.3
CustomFieldAdmin	0.2.6
Docutils	0.12
Genshi	0.7 (with speedups)
GIT	2.1.4
mod_wsgi	4.3.0 (WSGIProcessGroup WSGIApplicationGroup %{GLOBAL})
Pygments	2.0.1
pysqlite	2.6.0
Python	2.7.9 (default, Mar 1 2015, 13:01:26) [GCC 4.9.2]
pytz	2012c
setuptools	5.5.1
SQLite	3.8.7.1
Subversion	1.8.10 (r1615264)
jQuery	1.7.2
jQuery UI	1.10.1
jQuery Timepicker	1.2

Enabled Plugins

NavAdd	0.3
SimpleMultiProject	0.5.1dev
Trac-jsGantt	0.9
TracCustomFieldAdmin	0.2.6
TracMasterTickets	3.0.2
TracSubTicketsPlugin	0.1.1.dev-20120115

Python Traceback

Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/trac/web/main.py", line 512, in _dispatch_request
    dispatcher.dispatch(req)
  File "/usr/lib/python2.7/dist-packages/trac/web/main.py", line 240, in dispatch
    content_type)
  File "/usr/lib/python2.7/dist-packages/trac/web/chrome.py", line 1009, in render_template
    stream |= self._filter_stream(req, method, filename, stream, data)
  File "/usr/lib/python2.7/dist-packages/genshi/core.py", line 133, in __or__
    return Stream(_ensure(function(self)), serializer=self.serializer)
  File "/usr/lib/python2.7/dist-packages/trac/web/chrome.py", line 1192, in inner
    data)
  File "build/bdist.linux-x86_64/egg/simplemultiproject/roadmap.py", line 113, in filter_stream
    stream = stream | filter_.replace(HTML('<label for="showcompleted">Show completed milestones and '
  File "/usr/lib/python2.7/dist-packages/genshi/input.py", line 442, in HTML
    return Stream(list(HTMLParser(BytesIO(text), encoding=encoding)))
  File "/usr/lib/python2.7/dist-packages/genshi/core.py", line 273, in _ensure
    event = stream.next()
  File "/usr/lib/python2.7/dist-packages/genshi/input.py", line 449, in _coalesce
    for kind, data, pos in chain(stream, [(None, None, None)]):
  File "/usr/lib/python2.7/dist-packages/genshi/input.py", line 337, in _generate
    raise UnicodeError("source returned bytes, but no encoding specified")
UnicodeError: source returned bytes, but no encoding specified