[title slide]

Hi.

[context slide]

Sean Whitton and I are here to present a new git workflow tool for
Debian packaging.  It's primarily intended for Debian package
maintainers.  It's an alternative to gbp pq and to git-dpm.

Before I get tell you all about it I need to show where it fits into
the ecosystem of Debian package management software.  On this slide we
have you, the maintainer, on the left.  On the right we have the
Debian repositories.

You may have heard me plugging dgit once or twice.  You should all use
dgit!  dgit push publishes your git history so Debian's users can use
it!  But, that's not actually what I am here to talk about today.
git-debrebase does not need dgit, and dgit does not need
git-debrebase.

git-debrebase is a tool to help manage your git branch containing the
Debian version of a package you maintain.  git-debrebase helps you
maintain a useful git branch with the contents you need (for building
and uploading).

It maintains your Debian delta queue - that is, that is, the changes
you make, for Debian, to the upstream parts of the package - as a
series of commits.

[usp slide 1]

git-debrebase offers a standard git-rebase workflow, where you edit
the whole package all together.  The experience is very like using
plain git-rebase to edit a topic branch.  Delta queue editing can be
done at any time, interleaved with packaging work.

As you make new commits, you may make commits to upstream files, and
commits to packaging, in any order.  So you can just git-cherry-pick
from upstream.  You can make fixup commits, and use the git-rebase
autosquash syntax to have them automatically folded in by the next
rebase.  If you wish, you may make "mixed" commits containing both
changes to upstream files and changes to packaging files.

As far as I know there are no other tools that offer these features.
Both gbp pq and git-dpm require you to switch to a separate view in
order to edit the delta queue.  Some tools have specific functions for
cherry-pick, but with none of them you can just cherry pick or git-am
onto your current HEAD.

Of course you can always directly edit the source if you use a plain
git merge workflow and non-quilt source package - for example, as
described in the dgit-maint-merge tutorial manpage.  But of course
that does not maintain the Debian delta as a broken-down series.

Also, unlike git-dpm and some other tools, git-debrebase has no
in-tree metadata, so it can't get out of date or be desynchronised.

[usp slide 2]

Unlike with gbp pq and git-dpm, there is no need to ever switch
branches.  git-debrebase only uses one branch to handle all for your
Debian work.  (Usually you will have an upstream branch as well of
course, and if you are working in multiple Debian releases, backports
for example, you will have branches for those.)

Yowr working tree is always immediately buildable with
dpkg-buildpackage.  And it is never made dirty by git-debrebase or any
of the other tooling.  Because your working tree always has the delta
queue applied, it is never dirtied by patch application.  Because
there is no metadata, you can never get a metadata conflict.

Because git-debrebase treats the quilt patches in debian/patches/ as
an output, and handles them entirely automatically, your tree is never
dirtied by the generation of patches.  And you never need to read any
diffs of diffs.

[usp slide 3]

And, my last slide of non-bugs:

git-blame, and git-log on a file, work entirely properly.  For
example, if you do git-log on a file from upstream which was changed
in the Debian delta queue, git-log will show the Debian delta queue
commits, preceded by the upstream history.

If you run git-blame you will see a correct indication of which
upstream and/or delta queue commits introduced each line.  Or, for a
file in the debian directory, you will see a correct reporting of
which commits in the package's packaging history introduced each line.

With git-debrebase, you never need to use the quilt program.  You can
mostly ignore the 3.0 quilt source format.  (Unfortunately you will
still get trouble if you make changes in git which 3.0 quilt cannot
represent).

When you use git-debrebase with 3.0 quilt, the quilt output is always
perfect and pretty, just as other people consuming .dscs have come to
expect.

And finally: of course, git-debrebase is compatible with dgit.  You do
not need to pass any quilt mode option.  And, you always can upload
right away.  All necessary bureaucracy is done automatically by dgit
push-source.