videonote: Semantic fix according to CR

tsnoam · tsnoam · commit a5bfc523263e · 2017-05-26T18:36:21.000+03:00
diff --git a/telegram/bot.py b/telegram/bot.py
@@ -713,9 +713,9 @@ def send_video_note(self,
 
         data = {'chat_id': chat_id, 'video_note': video_note}
 
-        if duration:
+        if duration is not None:
             data['duration'] = duration
-        if length:
+        if length is not None:
             data['length'] = length
 
         return self._message_wrapper(
