* ds/commit-graph-lockfile-fix:
commit-graph: fix UX issue when .lock file exists
commit-graph.txt: update design document
merge: check config before loading commits
commit: use generation number in remove_redundant()
commit: add short-circuit to paint_down_to_common()
commit: use generation numbers for in_merge_bases()
ref-filter: use generation number for --contains
commit-graph: always load commit-graph information
commit: use generations in paint_down_to_common()
commit-graph: compute generation numbers
commit: add generation number to struct commit
ref-filter: fix outdated comment on in_commit_list