Merge branch 'kk/commit-reach-optim'

The check for non-stale commits in the priority queue used by `paint_down_to_common` and `ahead_behind` has been optimized by replacing an O(N) scan with an O(1) counter, yielding performance improvements in repositories with wide histories. * kk/commit-reach-optim: commit-reach: replace queue_has_nonstale() scan with O(1) tracking commit-reach: deduplicate queue entries in paint_down_to_common object.h: fix stale entries in object flag allocation table