Sync with 2.28.1

* maint-2.28:
  Git 2.28.1
  Git 2.27.1
  Git 2.26.3
  Git 2.25.5
  Git 2.24.4
  Git 2.23.4
  Git 2.22.5
  Git 2.21.4
  Git 2.20.5
  Git 2.19.6
  Git 2.18.5
  Git 2.17.6
  unpack_trees(): start with a fresh lstat cache
  run-command: invalidate lstat cache after a command finished
  checkout: fix bug that makes checkout follow symlinks in leading path

unpack-trees.c

@@ -417,6 +417,9 @@ static int check_updates(struct unpack_trees_options *o,
 
 	progress = get_progress(o, index);
 
+	/* Start with clean cache to avoid using any possibly outdated info. */
+	invalidate_lstat_cache();
+
 	git_attr_set_direction(GIT_ATTR_CHECKOUT);
 
 	if (should_update_submodules())