t1450: make hash size independent
Replace several hard-coded full and partial object IDs with variables or
computed values. Create junk data to stuff inside an invalid tree that
can be either 20 or 32 bytes long. Compute a binary all-zeros object ID
instead of hard-coding a 20-byte length.
Additionally, compute various object IDs by using test_oid and
$EMPTY_BLOB so that this test works with multiple hash algorithms.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>