[test] Fix `test_YoutubeDL.TestYoutubeDL`

Test `test_ignoreerrors_for_playlist_with_url_transparent_iterable_entries` was broken due to `__original_infodict` being added to the dict

test/test_YoutubeDL.py

@@ -29,6 +29,7 @@ class YDL(FakeYDL):
         self.msgs = []
 
     def process_info(self, info_dict):
+        info_dict.pop('__original_infodict', None)
         self.downloaded_info_dicts.append(info_dict)
 
     def to_screen(self, msg):