This test uses several index hashes, which necessarily depend on the
version of the index and the hash algorithm in use. Use test_oid_cache
to provide values for these for both SHA-1 and SHA-256. Also, compute
an object ID and use $EMPTY_BLOB to make the remainder of the tests
independent of the hash algorithm in use.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>