History of checkpoint 1 change

In crates/hub/src/flow.rs, lines 1509–1525 on v0.9.24. 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 1509,1525:crates/hub/src/flow.rs.