History of HubBackend::block 2 changes

In crates/hub/src/protocol.rs, lines 68–70 on bb018142cca7d18bd4f910c992653e74af783e8d2c7e80a98f9e5685553a7c63. 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 68,70:crates/hub/src/protocol.rs.