Midx repack has largely been used in Microsoft Scalar on the client side to
optimize the repository multiple packs state. However when I tried to apply
this onto the server-side, I realized that there are certain features that
were lacking compare to git repack. Most of these features are highly
desirable on the server-side to create the most optimized pack possible.

One of the example is delta_base_offset, comparing an midx repack
with/without delta_base_offset, we can observe significant size differences.

> du objects/pack/*pack
14536   objects/pack/pack-08a017b424534c88191addda1aa5dd6f24bf7a29.pack
9435280 objects/pack/pack-8829c53ad1dca02e7311f8e5b404962ab242e8f1.pack

Latest 2.26.2 (without delta_base_offset)
> git multi-pack-index write
> git multi-pack-index repack
> git multi-pack-index expire
> du objects/pack/*pack
9446096 objects/pack/pack-366c75e2c2f987b9836d3bf0bf5e4a54b6975036.pack

With delta_base_offset
> git version
git version 2.26.2.672.g232c24e857.dirty
> git multi-pack-index write
> git multi-pack-index repack
> git multi-pack-index expire
> du objects/pack/*pack
9152512 objects/pack/pack-3bc8c1ec496ab95d26875f8367ff6807081e9e7d.pack

Note that repack.writeBitmaps configuration is ignored, as the pack bitmap
facility is useful only with a single packfile.

Derrick Stolee's following patch will address repack.packKeptObjects
support.

Derrick Stolee (1):
  multi-pack-index: respect repack.packKeptObjects=false

Son Luong Ngoc (2):
  midx: teach "git multi-pack-index repack" honor "git repack"
    configurations
  Ensured t5319 follows arith expansion guideline

 Documentation/git-multi-pack-index.txt |  3 ++
 midx.c                                 | 36 ++++++++++++---
 t/t5319-multi-pack-index.sh            | 62 ++++++++++++++++++--------
 3 files changed, 78 insertions(+), 23 deletions(-)

base-commit: b994622632154fc3b17fb40a38819ad954a5fb88

Submitted-As: https://lore.kernel.org/git/pull.626.v3.git.1589034270.gitgitgadget@gmail.com
In-Reply-To: https://lore.kernel.org/git/pull.626.git.1588684003766.gitgitgadget@gmail.com
In-Reply-To: https://lore.kernel.org/git/pull.626.v2.git.1588758194.gitgitgadget@gmail.com