Fix for guessit returning a list for format

libs/subliminal/subtitle.py

@@ -238,7 +238,10 @@ def guess_matches(video, guess, partial=False):
     if video.resolution and 'screen_size' in guess and guess['screen_size'] == video.resolution:
         matches.add('resolution')
     # format
-    if video.format and 'format' in guess and guess['format'].lower() == video.format.lower():
+    # Guessit may return a list for `format`, which indicates a conflict in the guessing.
+    # We should match `format` only when it returns single value to avoid false `format` matches
+    if video.format and guess.get('format') and not isinstance(guess['format'], list) \
+            and guess['format'].lower() == video.format.lower():
         matches.add('format')
     # video_codec
     if video.video_codec and 'video_codec' in guess and guess['video_codec'] == video.video_codec: