[Logging] Fix Python 3.8 compatibility: https://git.deluge-torrent.org/deluge/commit/?h=develop&id=351664ec071daa04161577c6a1c949ed0f2c3206 [Logging] Fix findCaller with unknown source: https://git.deluge-torrent.org/deluge/commit/?h=develop&id=5e06aee5c8846f94bd5fcc209132dacf06de781f Fix warning related to gettext: https://git.deluge-torrent.org/deluge/commit/?h=develop&id=d6c96d629183e8bab2167ef56457f994017e7c85 Diff from Rob Schmersel, thanks!