[YoutubeDL] Encode thumbnail filename (Closes #6714)

youtube_dl/YoutubeDL.py

@@ -2009,7 +2009,7 @@ class YoutubeDL(object):
                                (info_dict['extractor'], info_dict['id'], thumb_display_id))
                 try:
                     uf = self.urlopen(t['url'])
-                    with open(thumb_filename, 'wb') as thumbf:
+                    with open(encodeFilename(thumb_filename), 'wb') as thumbf:
                         shutil.copyfileobj(uf, thumbf)
                     self.to_screen('[%s] %s: Writing thumbnail %sto: %s' %
                                    (info_dict['extractor'], info_dict['id'], thumb_display_id, thumb_filename))