The Debian packaging of farbfeld is maintained in git, using the merging
workflow described in dgit-maint-merge(7). There isn't a patch queue
that can be represented as a quilt series.

A detailed breakdown of the changes is available from their canonical
representation - git commits in the packaging repository. For example,
to see the changes made by the Debian maintainer in the first upload of
upstream version 3, you could use:

    % git clone https://git.dgit.debian.org/farbfeld
    % cd farbfeld
    % git log --oneline 3..debian/3-1 -- . ':!debian'

(If you have dgit, use `dgit clone farbfeld`, rather than plain `git
clone`.)

A single combined diff, containing all the changes, follows.