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