History of pack 1 change

In crates/flow/src/checkpoint.rs, lines 62–93 on f201e1bc5bcd764e0a2712d7c2ca21378cc5fe13a2ae62366b1095d87739e83c. 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 62,93:crates/flow/src/checkpoint.rs.