History of sigv4 1 change

In crates/hub/src/backups.rs, lines 457–482 on 5d818ec7d5fcbc9f08a9210d00cb0197705cd79eeeaf35507232317f440c6d27. 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.