t8002: make hash size independent

Compute the length of an object ID instead of hard-coding 40-based
values.

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

t/t8002-blame.sh

@@ -6,6 +6,10 @@ test_description='git blame'
 PROG='git blame -c'
 . "$TEST_DIRECTORY"/annotate-tests.sh
 
+test_expect_success 'setup' '
+	hexsz=$(test_oid hexsz)
+'
+
 test_expect_success 'blame untracked file in empty repo' '
 	>untracked &&
 	test_must_fail git blame untracked
@@ -105,17 +109,17 @@ test_expect_success 'blame --abbrev=<n> works' '
 '
 
 test_expect_success 'blame -l aligns regular and boundary commits' '
-	check_abbrev 40 -l HEAD &&
-	check_abbrev 39 -l ^HEAD
+	check_abbrev $hexsz         -l HEAD &&
+	check_abbrev $((hexsz - 1)) -l ^HEAD
 '
 
-test_expect_success 'blame --abbrev=40 behaves like -l' '
-	check_abbrev 40 --abbrev=40 HEAD &&
-	check_abbrev 39 --abbrev=40 ^HEAD
+test_expect_success 'blame --abbrev with full length behaves like -l' '
+	check_abbrev $hexsz         --abbrev=$hexsz HEAD &&
+	check_abbrev $((hexsz - 1)) --abbrev=$hexsz ^HEAD
 '
 
-test_expect_success '--no-abbrev works like --abbrev=40' '
-	check_abbrev 40 --no-abbrev
+test_expect_success '--no-abbrev works like --abbrev with full length' '
+	check_abbrev $hexsz --no-abbrev
 '
 
 test_expect_success '--exclude-promisor-objects does not BUG-crash' '