Merge branch 'jk/pack-objects-bitmap-progress-fix'

When "git pack-objects" makes a literal copy of a part of existing
packfile using the reachability bitmaps, its update to the progress
meter was broken.

* jk/pack-objects-bitmap-progress-fix:
  pack-objects: update "nr_seen" progress based on pack-reused count

diff --cc builtin/pack-objects.c
Simple merge

diff --cc t/t5310-pack-bitmaps.sh
Simple merge