Merge branch 'tb/pseudo-merge-bitmap-fixes'

We created a useless pseudo-merge reachability bitmap that is about 0 commits, and attempted to include commits that are not in packs, which made no sense. These bugs have been corrected. * tb/pseudo-merge-bitmap-fixes: pseudo-merge.c: ensure pseudo-merge groups are closed pseudo-merge.c: do not generate empty pseudo-merge commits t/t5333-pseudo-merge-bitmaps.sh: demonstrate empty pseudo-merge groups pack-bitmap-write.c: select pseudo-merges even for small bitmaps pack-bitmap: drop redundant args from `bitmap_writer_finish()` pack-bitmap: drop redundant args from `bitmap_writer_build()` pack-bitmap: drop redundant args from `bitmap_writer_build_type_index()` pack-bitmap: initialize `bitmap_writer_init()` with packing_data