[kgb-maintainers] Bug#821749: kgb-client: Support only notifying for "new to repo" commits in Git

[James McCoy]

Package: kgb-client
Version: 1.33-2
Severity: wishlist

The typical workflow I use for packaging in git is to work directly with
upstream sources and merge upstream tags into a Debian-specific branch
(c.f., https://anonscm.debian.org/cgit/pkg-vim/neovim.git).

I already have the post-receive hook filtering out any lines that match
refs/heads/master (i.e., upstream's code), which avoids floods for the
commit emails.  However, KGB still notifies for all of the upstream
commits that get pulled in by the merge, even though they're not "new"
to the repo when the merge commit is processed.

In #748397, it was suggested to use the squash_* git-config variables to
avoid the flood, but that's not very useful.  It forces me to remember
to push the merge commit on its own (so the related upstream commits are
squashed) and then continue pushing normally so there are typical
notices for packaging related commits.

Ideally, I'd like to handle this like git_multimail.py does, where a
specific commit is only notified when it is new to the repository,
not for every branch which contains the commit.

As a simpler/short-term solution, being able to notify the content that
“git log --ancestry-path old..new” shows would likely be a decent
compromise.  At least in my limited testing, that seems to avoid
notifying about every upstream commit while still including a
notification of the merge commit and any other commits to the packaging
branch.

-- System Information:
Debian Release: stretch/sid
  APT prefers unstable-debug
  APT policy: (500, 'unstable-debug'), (500, 'unstable'), (1, 'experimental-debug'), (1, 'experimental')
Architecture: amd64 (x86_64)
Foreign Architectures: i386, arm64

Kernel: Linux 4.5.0-1-amd64 (SMP w/4 CPU cores)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)