Merge branch 'ds/repack-fixlets'

Two fixes around "git repack".

* ds/repack-fixlets:
  repack: make '--quiet' disable progress
  repack: respect kept objects with '--write-midx -b'

diff --cc builtin/repack.c
Simple merge

diff --cc t/t7700-repack.sh
Simple merge

diff --cc t/test-lib-functions.sh
Simple merge