That section of the guide is a bit poorly worded. You should *not* use "git add"
on source tarballs. These should be added only via means of "fedpkg new-sources
$FILES; git add ./sources". I believe what the guide means under "new source
files" is e.g. when upstream does not provide an icon or a .desktop or an
.appdata.xml file (or a systemd .service or whatever) and you add your own. This does not
include "new upstream release tarball".
I'll try to think of some way to make that more clear and submit a suggestion to
change the guide text.