tree-diff.c: remove implicit dependency on the_index

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

tree-diff.c

@@ -605,7 +605,7 @@ static void try_to_follow_renames(const struct object_id *old_oid,
 	choice = q->queue[0];
 	q->nr = 0;
 
-	repo_diff_setup(the_repository, &diff_opts);
+	repo_diff_setup(opt->repo, &diff_opts);
 	diff_opts.flags.recursive = 1;
 	diff_opts.flags.find_copies_harder = 1;
 	diff_opts.output_format = DIFF_FORMAT_NO_OUTPUT;