Merge branch 'jc/topo-author-date-sort'

"git log" learned the "--author-date-order" option, with which the output is topologically sorted and commits in parallel histories are shown intermixed together based on the author timestamp. * jc/topo-author-date-sort: t6003: add --author-date-order test topology tests: teach a helper to set author dates as well t6003: add --date-order test topology tests: teach a helper to take abbreviated timestamps t/lib-t6000: style fixes log: --author-date-order sort-in-topological-order: use prio-queue prio-queue: priority queue of pointers to structs toposort: rename "lifo" field