W: Size of file /var/lib/apt/lists/partial/www.whonix.org_download_whonixdevelopermetafiles_internal_dists_jessie_main_binary-amd64_Packages.gz is not what the server reported
It's harmless. (Has to do with our server setup. /download was
re-purposed for the new homepage. Old apt sources list uris are still
using /download/whonixdevelopermetafiles rather than deb.whonix.org. And
the apache redirection isn't perfect.)
Fixed in Whonix 14. Maybe also will be fixed in Whonix 13.
Or manually change to the new apt sources list uri.
sudo whonix_repository --baseuri http://deb.whonix.org --enable --repository stable