t1007: choose the built-in hash outside of a repo

Right now, the built-in default hash is always SHA-1, but that will
change in a future commit.  Instead of assuming that operating outside
of a repository will always use SHA-1, simply ask test_oid for the
built-in hash instead, which will always be correct.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: bk2204

t/t1007-hash-object.sh

@@ -252,9 +252,9 @@ test_expect_success '--literally complains about non-standard types' '
 	test_must_fail git hash-object -t bogus --literally --stdin
 '
 
-test_expect_success '--stdin outside of repository (uses SHA-1)' '
+test_expect_success '--stdin outside of repository (uses default hash)' '
 	nongit git hash-object --stdin <hello >actual &&
-	echo "$(test_oid --hash=sha1 hello)" >expect &&
+	echo "$(test_oid --hash=builtin hello)" >expect &&
 	test_cmp expect actual
 '