Merge branch 'td/ref-filter-memoize-contains' into jch

'git branch --contains' and 'git for-each-ref --contains' have been optimized to use the memoized commit traversal previously used only by 'git tag --contains', significantly speeding up connectivity checks across many candidate refs with shared history. * td/ref-filter-memoize-contains: commit-reach: die on contains walk errors ref-filter: memoize --contains with generations commit-reach: reject cycles in contains walk