grep: use the right index instead of the_index

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

builtin/grep.c

@@ -497,7 +497,7 @@ static int grep_cache(struct grep_opt *opt, struct repository *repo,
 		strbuf_addstr(&name, ce->name);
 
 		if (S_ISREG(ce->ce_mode) &&
-		    match_pathspec(&the_index, pathspec, name.buf, name.len, 0, NULL,
+		    match_pathspec(repo->index, pathspec, name.buf, name.len, 0, NULL,
 				   S_ISDIR(ce->ce_mode) ||
 				   S_ISGITLINK(ce->ce_mode))) {
 			/*
@@ -515,7 +515,7 @@ static int grep_cache(struct grep_opt *opt, struct repository *repo,
 				hit |= grep_file(opt, name.buf);
 			}
 		} else if (recurse_submodules && S_ISGITLINK(ce->ce_mode) &&
-			   submodule_path_match(&the_index, pathspec, name.buf, NULL)) {
+			   submodule_path_match(repo->index, pathspec, name.buf, NULL)) {
 			hit |= grep_submodule(opt, repo, pathspec, NULL, ce->name, ce->name);
 		} else {
 			continue;