Ignore image enclosures for audio/video in Media RSS (bug 1430)

We have only checked if audio and/or video is available in
normal enclosures. This check is now extended to Media RSS
items, because there are feeds that have the image as
enclosure and the media file as Media RSS content.

Example feed: http://www.rtl.fr/emission/a-la-bonne-heure.rss

(This commit has been merged from the "tres" branch)

src/gpodder/model.py

@@ -712,10 +712,11 @@ def from_feedparser_entry(entry, channel, mimetype_prefs=''):
             episode.pubDate = rfc822.mktime_tz(entry.updated_parsed+(0,))
 
         enclosures = entry.get('enclosures', ())
+        media_rss_content = entry.get('media_content', ())
         audio_available = any(e.get('type', '').startswith('audio/') \
-                for e in enclosures)
+                for e in enclosures + media_rss_content)
         video_available = any(e.get('type', '').startswith('video/') \
-                for e in enclosures)
+                for e in enclosures + media_rss_content)
 
         # Create the list of preferred mime types
         mimetype_prefs = mimetype_prefs.split(',')
@@ -746,6 +747,7 @@ def calculate_preference_value(enclosure):
                 continue
 
             # Skip images in feeds if audio or video is available (bug 979)
+            # This must (and does) also look in Media RSS enclosures (bug 1430)
             if episode.mimetype.startswith('image/') and \
                     (audio_available or video_available):
                 continue
@@ -762,11 +764,14 @@ def calculate_preference_value(enclosure):
             return episode
 
         # Media RSS content
-        for m in entry.get('media_content', ()):
+        for m in sorted(media_rss_content, key=calculate_preference_value):
             episode.mimetype = m.get('type', 'application/octet-stream')
             if '/' not in episode.mimetype:
                 continue
 
+            # XXX: Does Media RSS content also have images? If so, we
+            # might want to skip these too (see above for enclosures).
+
             episode.url = util.normalize_feed_url(m.get('url', ''))
             if not episode.url:
                 continue