WebAgg favicon serving error in Python 3

[mdboom]

backend_webagg.py, near line 381:

class FavIcon(tornado.web.RequestHandler):
        def get(self):
            self.set_header('Content-Type', 'image/png')
            with open(os.path.join(WebAggApplication._mpl_dirs['images'],
                                   'matplotlib.png')) as fd:
                self.write(fd.read())

Doing self.write(fd.read()) is an error: Tornado converts everything passed into write() to utf-8 at least in Python 3, so that I get the following runtime error after opening a web browser:

Traceback (most recent call last):
File "/usr/lib/python3/dist-packages/tornado/web.py", line 1042, in _execute
getattr(self, self.request.method.lower())(_args, *_kwargs)
File "/usr/lib/python3/dist-packages/matplotlib/backends/backend_webagg.py", line 381, in get
self.write(fd.read())
File "/usr/lib/python3.3/codecs.py", line 300, in decode
(result, consumed) = self._buffer_decode(data, self.errors, final)
UnicodeDecodeError: 'utf-8' codec can't decode byte 0x89 in position 0: invalid start byte

This error is reasonable: trying to convert binary data - matplotlib.png - to utf8 is definitely a bad idea. I am not sure how to fix it, as I am novice to Tornado and Python in general.

[pelson]

Thanks for reporting @vmarkovtsev. I'm sure we can get this fixed up in pretty short order.

[mdboom]

I'm working on a fix now...

[mdboom]

A fix is attached. Note that to reproduce, you may need to hit the "refresh" button in your browser to get it to re-fetch the favicon.