History of sigv4 1 change

In crates/hub/src/backups.rs, lines 457–482 on 91c306aa47061a18f85e0109fa9d757a014b7267f8c14b4412a498cee9976e67. 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 457,482:crates/hub/src/backups.rs.