cache-tree.c: remove the_repository references

This case is more interesting than other boring "remove the_repo"
commits because while we need access to the object database, we cannot
simply use r->index because unpack-trees.c can operate on a temporary
index, not $GIT_DIR/index. Ideally we should be able to pass an object
database to lookup_tree() but that ship has sailed.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/builtin/reset.c b/builtin/reset.c
index 5b4bbb0..161b5e0 100644
--- a/builtin/reset.c
+++ b/builtin/reset.c
@@ -93,7 +93,7 @@ static int reset_index(const struct object_id *oid, int reset_type, int quiet)
 
 	if (reset_type == MIXED || reset_type == HARD) {
 		tree = parse_tree_indirect(oid);
-		prime_cache_tree(&the_index, tree);
+		prime_cache_tree(the_repository, the_repository->index, tree);
 	}
 
 	ret = 0;