Merge branch 'tb/midx-repack-ignore-cruft-packs'
"git multi-pack-index repack/expire" used to repack unreachable
cruft into a new pack, which have been corrected.
* tb/midx-repack-ignore-cruft-packs:
midx.c: avoid cruft packs with non-zero `repack --batch-size`
midx.c: remove unnecessary loop condition
midx.c: replace `xcalloc()` with `CALLOC_ARRAY()`
midx.c: avoid cruft packs with `repack --batch-size=0`
midx.c: prevent `expire` from removing the cruft pack
Documentation/git-multi-pack-index.txt: clarify expire behavior
Documentation/git-multi-pack-index.txt: fix typo