Merge branch 'bc/maint-keep-pack'

Merge branch 'bc/maint-keep-pack'

* bc/maint-keep-pack:
  t7700: test that 'repack -a' packs alternate packed objects
  pack-objects: extend --local to mean ignore non-local loose objects too
  sha1_file.c: split has_loose_object() into local and non-local counterparts
  t7700: demonstrate mishandling of loose objects in an alternate ODB
  builtin-gc.c: use new pack_keep bitfield to detect .keep file existence
  repack: do not fall back to incremental repacking with [-a|-A]
  repack: don't repack local objects in packs with .keep file
  pack-objects: new option --honor-pack-keep
  packed_git: convert pack_local flag into a bitfield and add pack_keep
  t7700: demonstrate mishandling of objects in packs with a .keep file