fsck: verify multi-pack-index when implictly enabled

Like the previous commit, change fsck to check the
"core_multi_pack_index" variable set in "repo-settings.c" instead of
reading the "core.multiPackIndex" config variable. This fixes a bug
where we wouldn't verify midx if the config key was missing. This bug
was introduced in 18e449f (midx: enable core.multiPackIndex by
default, 2020-09-25) where core.multiPackIndex was turned on by default.

Helped-by: Ævar Arnfjörð Bjarmason <[email protected]>
Signed-off-by: Glen Choo <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: chooglen

builtin/fsck.c

@@ -925,7 +925,7 @@ int cmd_fsck(int argc, const char **argv, const char *prefix)
 		}
 	}
 
-	if (!git_config_get_bool("core.multipackindex", &i) && i) {
+	if (the_repository->settings.core_multi_pack_index) {
 		struct child_process midx_verify = CHILD_PROCESS_INIT;
 		const char *midx_argv[] = { "multi-pack-index", "verify", NULL, NULL, NULL };
 

t/t5319-multi-pack-index.sh

@@ -452,7 +452,10 @@ test_expect_success 'verify incorrect offset' '
 test_expect_success 'git-fsck incorrect offset' '
 	corrupt_midx_and_verify $MIDX_BYTE_OFFSET "\377" $objdir \
 		"incorrect object offset" \
-		"git -c core.multipackindex=true fsck"
+		"git -c core.multiPackIndex=true fsck" &&
+	test_unconfig core.multiPackIndex &&
+	test_must_fail git fsck &&
+	git -c core.multiPackIndex=false fsck
 '
 
 test_expect_success 'corrupt MIDX is not reused' '