Merge branch 'mk/maint-parse-careful'

* mk/maint-parse-careful:
  receive-pack: use strict mode for unpacking objects
  index-pack: introduce checking mode
  unpack-objects: prevent writing of inconsistent objects
  unpack-object: cache for non written objects
  add common fsck error printing function
  builtin-fsck: move common object checking code to fsck.c
  builtin-fsck: reports missing parent commits
  Remove unused object-ref code
  builtin-fsck: move away from object-refs to fsck_walk
  add generic, type aware object chain walker

Conflicts:

	Makefile
	builtin-fsck.c

builtin-fetch-pack.c

@@ -386,7 +386,6 @@ static int everything_local(struct ref **refs, int nr_match, char **match)
 	int retval;
 	unsigned long cutoff = 0;
 
-	track_object_refs = 0;
 	save_commit_buffer = 0;
 
 	for (ref = *refs; ref; ref = ref->next) {