Revert "check backup date on symlink instead of dir"

This reverts commit 3848da13.

tests/test_backup.py

@@ -83,7 +83,7 @@ def test_last_backup_is_recent(server: str) -> bool:
     # test each possible path
     for path in paths:
         # build and run commands
-        find = "find -L {} {} {} {}".format(
+        find = "find -L {} {} {} {} {}".format(
             path,
             "-maxdepth 1",
             "-xtype l",