[MKV Thumbnail Support] Now has the correct file name in MKV container

diff --cc youtube_dl/postprocessor/embedthumbnail.py
index 4393c4e7a9176ba53a0feca70fc4f1254dbd81d1,eae266dde7e18123dae92696912203a25244a436..795582259082deda4707a902d44426c42d578695
--- 1/youtube_dl/postprocessor/embedthumbnail.py
--- 2/youtube_dl/postprocessor/embedthumbnail.py
+++ b/youtube_dl/postprocessor/embedthumbnail.py
@@@ -55,11 -55,7 +55,15 @@@ class EmbedThumbnailPP(FFmpegPostProces
              os.remove(encodeFilename(filename))
              os.rename(encodeFilename(temp_filename), encodeFilename(filename))
  
++<<<<<<< HEAD
 +        elif info['ext'] == 'mkv':
 +            os.rename(encodeFilename(thumbnail_filename), encodeFilename('cover.jpg'))
 +            old_thumbnail_filename = thumbnail_filename
 +            thumbnail_filename = 'cover.jpg'
 +
++=======
+         if info['ext'] == 'mkv':
++>>>>>>> a0b2ee64dbe6d4bedad9883cc8014aa77cdd0138
              options = [
                  '-c', 'copy', '-attach', thumbnail_filename, '-metadata:s:t', 'mimetype=image/jpeg']
  
@@@ -69,8 -65,6 +73,11 @@@
  
              if not self._already_have_thumbnail:
                  os.remove(encodeFilename(thumbnail_filename))
++<<<<<<< HEAD
 +            else:
 +                os.rename(encodeFilename(thumbnail_filename), encodeFilename(old_thumbnail_filename))
++=======
++>>>>>>> a0b2ee64dbe6d4bedad9883cc8014aa77cdd0138
              os.remove(encodeFilename(filename))
              os.rename(encodeFilename(temp_filename), encodeFilename(filename))