Merge branch 'tb/multi-pack-reuse-fix'

Assorted fixes to multi-pack-index code paths. * tb/multi-pack-reuse-fix: pack-revindex.c: guard against out-of-bounds pack lookups pack-bitmap.c: avoid uninitialized `pack_int_id` during reuse midx-write.c: do not read existing MIDX with `packs_to_include`