I'm playing around with the new upload implementation in site and chunked uploading. Chunked uploading seems to work ok, but on every upload I get a warning:

2016-04-23 08:53:29 api.py, 1925 in submit: VERBOSE Submitting unthrottled action 'upload'.
.... (repeated for every chunk)
2016-04-23 08:54:31 api.py, 1925 in submit: VERBOSE Submitting unthrottled action 'upload'.
2016-04-23 08:54:40 site.py, 5900 in upload: WARNING Offset was not supplied.
2016-04-23 08:54:40 site.py, 5903 in upload: VERBOSE Finished uploading last chunk.
2016-04-23 08:54:49 site.py, 5978 in upload: INFO Upload successful.

My assumption is that the last chunk isn't handled properly triggering this warning.
Pywikibot version Pywikibot: [https] r-pywikibot-core.git (75134ba, g7223, 2016/04/21, 22:05:31, ok)