Bug#952523: udd/autoremovals.cgi: please allow inspecting the dependency chain to the buggy package

[Johannes 'josch' Schauer <josch@debian.org>]

Package: qa.debian.org
Severity: wishlist

Hi,

I just got an autoremoval on by package src:botch:

    botch: buggy deps gtksourceview2, flagged for removal in 29.7 days

Since I never heard of the package gtksourceview2 in my whole time as a
DD I was puzzled why this package affected mine in the first place. One
possible dependency chain seems to be:

    src:botch
    -> libatdgen-ocaml-dev
    -> src:ocaml-atd
    -> menhir
    -> src:menhir
    -> coq
    -> src:coq
    -> liblablgtksourceview2-ocaml-dev
    -> libgtksourceview2.0-dev
    -> src:gtksourceview2

This is useful information for me because now I know which other
packages I might want to contribute to, to solve this issue.
Unfortunately, it is not easy to get this reverse dependency chain.
Maybe it could be printed into autoremovals.cgi by default or there
could be a parameter so that one could retrieve it?

For the record, I obtained above chain by first creating a dependency
graph including all dependency, build-dependency and builds-from
relationships like this:

    $ dose-ceve -T grml --deb-builds-from --deb-native-arch=amd64 debsrc://Sources deb://Packages > /tmp/graph.xml

And then extracted the shortest path from src:botch to
src:gtksourceview2 using:

    $ botch-graph-shortest-path /tmp/graph.xml /tmp/out.xml --source realpackage:src:botch --target realpackage:src:gtksourceview2

Maybe there is an easier way but even if it is out of scope for
autoremovals.cgi to also show one of the dependency paths, maybe a
recipe of how to compute such a path could be documented somewhere?

Thanks!

cheers, josch