dirstate-v2: skip evaluation of hgignore regex on cached directories By making the computation of [has_ignored_ancestor] lazy we're eliding its computation in the common case when none of its descendants have changed on disk. On a ~400k files repo, with a cached status, we saw a ~64% reduction in CPU time, resulting in a speedup of ~10-15% (on ZFS), and a speedup of ~38% of XFS (XFS has faster stat operations for some reason).