[PATCH 0/5] pack-objects: brown-paper-bag fixes for multi-pack reuse

This series fixes a couple of issues (some cosmetic, others less so) in multi-pack reuse noticed when rolling this out over a few real-world, internal repositories on GitHub's servers.

The patches are laid out as follows:

  - The first three patches demonstrate, prepare for, and fix a
    significant bug with multi-pack reuse which results in all sorts of
    strange behavior (explained in detail in the third commit of this
    series).

  - The fourth patch is a minor (mostly cosmetic) performance
    optimization that avoids duplicate calls to pack_pos_to_offset()
    when performing pack-reuse with a MIDX bitmap.

  - The final patch is a cosmetic fix to avoid using the value of a
    constant instead of the name constant itself.

Thanks in advance for your review!

Taylor Blau (5):
  t/t5332-multi-pack-reuse.sh: verify pack generation with --strict
  pack-bitmap: tag bitmapped packs with their corresponding MIDX
  builtin/pack-objects.c: translate bit positions during pack-reuse
  pack-bitmap.c: avoid repeated `pack_pos_to_offset()` during reuse
  builtin/pack-objects.c: do not open-code `MAX_PACK_OBJECT_HEADER`

 builtin/pack-objects.c      | 46 +++++++++++++++++++++++++++++--------
 midx.c                      |  1 +
 pack-bitmap.c               | 12 ++++++----
 pack-bitmap.h               |  1 +
 t/t5332-multi-pack-reuse.sh | 35 ++++++++++++++++++++++++----
 5 files changed, 78 insertions(+), 17 deletions(-)

base-commit: 159f2d50e75c17382c9f4eb7cbda671a6fa612d1