Postprocessors: use a list for the files that can be deleted

We could only know if we had to delete the original file, but this system allows to specify us more files (like subtitles).

1 files changed, 4 insertions, 4 deletions

diff --git a/youtube_dl/postprocessor/common.py b/youtube_dl/postprocessor/common.py
index ef9fdfa19..3b0e8ddd8 100644
--- a/youtube_dl/postprocessor/common.py
+++ b/youtube_dl/postprocessor/common.py
@@ -42,14 +42,14 @@ class PostProcessor(object):
         one has an extra field called "filepath" that points to the
         downloaded file.
 
-        This method returns a tuple, the first element of which describes
-        whether the original file should be kept (i.e. not deleted - None for
-        no preference), and the second of which is the updated information.
+        This method returns a tuple, the first element is a list of the files
+        that can be deleted, and the second of which is the updated
+        information.
 
         In addition, this method may raise a PostProcessingError
         exception if post processing fails.
         """
-        return None, information  # by default, keep file and do nothing
+        return [], information  # by default, keep file and do nothing
 
     def try_utime(self, path, atime, mtime, errnote='Cannot update utime of file'):
         try: