Bug#850478: git-pbuilder deliberately deletes source.changes

[James Clarke]

Package: git-buildpackage
Version: 0.8.9
Severity: important
X-Debbugs-Cc: Debian pbuilder maintenance team <pbuilder-maint at lists.alioth.debian.org>

Disclaimer: These views are my own and not necessarily shared with
Mattia; he has the final say with regards to pbuilder :)

Hi,
Currently, straight after git-pbuilder invokes pdebuild, it deletes
../*_source.changes, provided there is at least one such file, and the
build was not done with -S. This causes two problems:

 1. It ignores version numbers and package names, causing potential data
    loss, which I feel is justification enough for the Severity: important.
    While it's a data loss bug, I don't think it's major enough to be RC.
    (Please clone this if you want to separate this bug from the point
    below...)

 2. I like being able to perform source-only uploads. While you can get
    pbuilder to generate a source-only changes file for a source+binary
    build with --changes-option=-S, this has the unfortunate side-effect
    of not copying back the .deb files, since they aren't referenced by
    the .changes. Also, the changes file is _arch.changes, which is
    misleading, and having the real _arch.changes is useful. Thus, I
    would like to have a --source-only-changes option which functions
    like sbuild (the main dpkg-buildpackage invocation generates
    _arch.changes, and then a manual dpkg-genchanges --build=source is
    performed) so that users can get both from one build.

    In looking into this, I discovered that pdebuild itself actually
    ends up producing a _source.changes, since it calls
    dpkg-buildpackage -S to generate the dsc to copy into the chroot. I
    presume that the original intention of the deletion performed by
    git-pbuilder was to delete *this* changes file, since the dsc
    subsequently produced by the build inside the chroot will not be
    identical, but is copied back as part of the build, making the
    original _source.changes invalid.

    Now, I'm of the view that dpkg-source -b should be used instead,
    which is what sbuild uses to create the dsc. This also has the
    advantage of not generating .buildinfo files (no annoying
    debian/files lingering after the build, either). Then the only
    _source.changes generated by pbuilder would be if the user requested
    it, and therefore having it deleted by git-pbuilder would be wrong.
    I should think changes like this are too late for Stretch, but
    perhaps for Buster (or experimental?) we could coordinate our
    efforts to get this to work?

    This is not just hypothetical, either; I actually have patched
    git-pbuilder[1] and pbuilder to implement this, but the implications
    of the switch to dpkg-source -b would need to be discussed

I appreciate this is a lot of irrelevant details, but I hope by
explaining where we are and where I'd like to get to makes the issues
clear. A lot of this will end up going into a bug report against
pbuilder blocked by this tomorrow.

Regards,
James

[1] Commented out the 3-line if statement that deletes _source.changes