History of checkpointer 2 changes

In crates/hub/src/tlog.rs, lines 612–629 on cancel-landed-runs. Every change that wrote or deleted one of these lines, or deleted a line from between them. Exact, because each line keeps its identity across edits; edits elsewhere in the file are not here. Also: oxy log -L 612,629:crates/hub/src/tlog.rs.