Merge branch 'tb/geom-repack-with-keep-and-max'

Teach "git repack --geometric" work better with "--keep-pack" and
avoid corrupting the repository when packsize limit is used.

* tb/geom-repack-with-keep-and-max:
  builtin/repack.c: ensure that `names` is sorted
  t7703: demonstrate object corruption with pack.packSizeLimit
  repack: respect --keep-pack with geometric repack