Merge branch 'ak/corrected-commit-date'

The commit-graph learned to use corrected commit dates instead of
the generation number to help topological revision traversal.

* ak/corrected-commit-date:
  doc: add corrected commit date info
  commit-reach: use corrected commit dates in paint_down_to_common()
  commit-graph: use generation v2 only if entire chain does
  commit-graph: implement generation data chunk
  commit-graph: implement corrected commit date
  commit-graph: return 64-bit generation number
  commit-graph: add a slab to store topological levels
  t6600-test-reach: generalize *_three_modes
  commit-graph: consolidate fill_commit_graph_info
  revision: parse parent in indegree_walk_step()
  commit-graph: fix regression when computing Bloom filters

upload-pack.c

@@ -493,7 +493,7 @@ static int got_oid(struct upload_pack_data *data,
 
 static int ok_to_give_up(struct upload_pack_data *data)
 {
-	uint32_t min_generation = GENERATION_NUMBER_ZERO;
+	timestamp_t min_generation = GENERATION_NUMBER_ZERO;
 
 	if (!data->have_obj.nr)
 		return 0;