History of checkpoint 2 changes

In crates/hub/src/tlog.rs, lines 716–721 on ea55fb62f9197f55862753612441467a6f1598cf418867be0fae48736ac803b8. 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 716,721:crates/hub/src/tlog.rs.