./configure --with-python3 fails when python3.4 is the installed version of python3.

(mediagoblin-0.8.0-dev) ~/mediagoblin $ python --version
Python 3.4.3
(mediagoblin-0.8.0-dev) ~/mediagoblin $ ./configure --with-python3
checking for python3.3... no
configure: error: in `/srv/mediagoblin/mediagoblin':
configure: error: --with-python3 given but no acceptable python3 (3.3) could be found
See `config.log' for more details

I'm going to set a milestone of 0.9.0 on here because of ticket #5017.

Running

./bin/gmg dbupdate

produces the following backtrace:

​https://gist.github.com/mrvdb/b1f6ed39af8eb5a84944

I get this error when trying to upload a working mp4 file, using current master (​https://gitorious.org/mediagoblin/mediagoblin/commit/714008693e08fc8a229fb3f7822c70c132aade7f). The same file is processed successfully on 0.7.2-dev.

2015-03-15 11:24:14,893 INFO    [mediagoblin.media_types] Info about file found, checking further
2015-03-15 11:24:14,893 INFO    [mediagoblin.media_types] checking the contents with sniffer
2015-03-15 11:24:14,893 INFO    [mediagoblin.media_types.video.processing] Sniffing mediagoblin.media_types.video
2015-03-15 11:24:14,893 INFO    [mediagoblin.media_types.tools] Discovering /tmp/tmpn4ekgH...
2015-03-15 11:24:14,898 WARNING [mediagoblin.media_types.video.processing] GStreamer: gst-stream-error-quark: This file is incomplete and cannot be played. (9)
2015-03-15 11:24:14,898 INFO    [mediagoblin.media_types] sniffer says it will not accept the file
2015-03-15 11:24:14,899 DEBUG   [mediagoblin.media_types] GStreamer: gst-stream-error-quark: This file is incomplete and cannot be played. (9)