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/read-tree.c b/builtin/read-tree.c
index fbbc98e..c05c12d 100644
--- a/builtin/read-tree.c
+++ b/builtin/read-tree.c
@@ -255,7 +255,9 @@ int cmd_read_tree(int argc, const char **argv, const char *unused_prefix)
 	 * what came from the tree.
 	 */
 	if (nr_trees == 1 && !opts.prefix)
-		prime_cache_tree(&the_index, trees[0]);
+		prime_cache_tree(the_repository,
+				 the_repository->index,
+				 trees[0]);
 
 	if (write_locked_index(&the_index, &lock_file, COMMIT_LOCK))
 		die("unable to write new index file");