Merge branch 'tb/bitmap-walk-with-tree-zero-filter'

The object walk with object filter "--filter=tree:0" can now take advantage of the pack bitmap when available. * tb/bitmap-walk-with-tree-zero-filter: pack-bitmap: pass object filter to fill-in traversal pack-bitmap.c: support 'tree:0' filtering pack-bitmap.c: make object filtering functions generic list-objects-filter: treat NULL filter_options as "disabled"