Re: [PATCH v2 2/2] commit: detect commits that exist in commit-graph but not in the ODB

> @@ -572,8 +573,21 @@ int repo_parse_commit_internal(struct repository *r,
>  		return -1;
>  	if (item->object.parsed)
>  		return 0;
> -	if (use_commit_graph && parse_commit_in_graph(r, item))
> +	if (use_commit_graph && parse_commit_in_graph(r, item)) {
> +		static int object_paranoia = -1;
> +
> +		if (object_paranoia == -1)
> +			object_paranoia = git_env_bool(GIT_COMMIT_GRAPH_PARANOIA, 1);

> @@ -842,4 +842,31 @@ test_expect_success 'stale commit cannot be parsed when given directly' '
>  	)
>  '
>
> +test_expect_success 'stale commit cannot be parsed when traversing graph' '
> +	test_when_finished "rm -rf repo" &&
> +	git init repo &&
> +	(
> +		cd repo &&
> +
> +		test_commit A &&
> +		test_commit B &&
> +		test_commit C &&
> +		git commit-graph write --reachable &&
> +
> +		# Corrupt the repository by deleting the intermittent commit

> +		# object. Commands should notice that this object is absent and
> +		# thus that the repository is corrupt even if the commit graph
> +		# exists.
> +		oid=$(git rev-parse B) &&
> +		rm .git/objects/"$(test_oid_to_path "$oid")" &&
> +
> +		# Again, we should be able to parse the commit when not
> +		# being paranoid about commit graph staleness...
> +		GIT_COMMIT_GRAPH_PARANOIA=false git rev-parse HEAD~2 &&
> +		# ... but fail when we are paranoid.
> +		test_must_fail git rev-parse HEAD~2 2>error &&
> +		grep "error: commit $oid exists in commit-graph but not in the object database" error
> +	)