[downloader/hls] Properly close stream

youtube_dl/downloader/hls.py

@@ -92,6 +92,7 @@ class NativeHlsFD(FragmentFD):
                 return False
             down, frag_sanitized = sanitize_open(frag_filename, 'rb')
             ctx['dest_stream'].write(down.read())
+            down.close()
             frags_filenames.append(frag_sanitized)
 
         self._finish_frag_download(ctx)