git index-pack by default reads the repository to determine the object
format. However, when outside of a repository, it's necessary to specify
the hash algorithm in use so that the pack can be properly indexed. Add
an --object-format argument when invoking git index-pack outside of a
repository.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>