From: Jeff King <peff@peff.net>
Date: Sat, 21 Dec 2013 14:23:37 GMT
Subject: [PATCH 0/2] cat-file --batch-check='%(deltabase)'
Message-ID: <20131221142336.GA28649@sigill.intra.peff.net>

This series lets you query the delta base for a particular object (or
set of objects), like:

  $ git rev-list --objects --all |
    git cat-file --batch-check='%(objectname) %(deltabase) %(rest)'

The only other way I know of to get this information is using
verify-pack (or index-pack), which is much slower (and less convenient
to parse).

I needed this recently to write tests for another (not yet published)
series. But I think it stands on its own as a debugging / introspection
tool.

  [1/2]: sha1_object_info_extended: provide delta base sha1s
  [2/2]: cat-file: provide %(deltabase) batch format

-Peff