Merge branch 'mh/replace-refs-variable-rename'

* mh/replace-refs-variable-rename:
Document some functions defined in object.c
Add docstrings for lookup_replace_object() and do_lookup_replace_object()
rename read_replace_refs to check_replace_refs

diff --cc builtin/fsck.c
Simple merge

diff --cc builtin/pack-objects.c
Simple merge

diff --cc builtin/prune.c
Simple merge

diff --cc builtin/replace.c
Simple merge

diff --cc builtin/unpack-objects.c
Simple merge

diff --cc cache.h
Simple merge

diff --cc replace_object.c
Simple merge