[pkg-apparmor] Bug#888244: apparmor: Convert quilt patch series to per-topic subdirectories managed by gbp-pq

[Simon McVittie]

On Wed, 24 Jan 2018 at 09:23:16 +0100, intrigeri at debian.org wrote:
> Thankfully there's a way to store this metadata in a more structured
> way: we can store patches in sub-directories of d/patches/ and use
> gbp-pq's "topic" concept. For example, see how it's done for
> src:systemd:
> https://anonscm.debian.org/git/pkg-systemd/systemd.git/tree/debian/README.source?h=debian/236-3#n28

I also use a version of this for dbus and the bubblewrap/ostree/flatpak
group of packages. The difference in those packages is that I use
"topic 1.2.3" for patches that have been successfully upstreamed and
were released in 1.2.3 or are expected to be released in a future 1.2.3;
the empty topic contains patches that have been sent upstream (or could
in principle be sent upstream) but have not been accepted or rejected yet.

For packages where you stay close to upstream that's perhaps unnecessary
complexity, but I've found it useful with upstreams where Debian is unable
to follow the latest upstream releases (like policykit-1), and for dbus
packages in a Debian derivative where I was following the upstream stable
branch but importing a few large features from the development branch.

> In particular I'd welcome input from Simon who, I believe, has built
> extensive experience with using gbp-pq's "topic" concept in
> similar situation.

Well, obviously I like this idea :-)

One more thing that I'd suggest: sort the patch series by "closest to
upstream", upstreamed patches < upstreamable patches < Debian-local
changes < derivatives' changes, so that rebasing on a new upstream
consists of dropping a prefix of the patch series (and replacing it with
a new upstream that already contains those commits), and upstreamable
patches have the maximum chance of being directly applicable upstream and
not becoming entangled in downstream changes. apparmor in Debian has not
historically done this: Debian- and Ubuntu-specific patches come before
upstreamed and upstreamable patches, which always seemed strange to me.

    smcv