History of HubBackend::block 2 changes

In crates/hub/src/protocol.rs, lines 68–70 on 2a8b621676b42cbc143f985eb3226e83d515504dda995db118836ab6beb672f6. 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.