History of HubBackend::block 2 changes

In crates/hub/src/protocol.rs, lines 51–53 on a1b9869565aad8c8b391208f64eba146178677c739c7374a95f0b2be8f44723d. 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 51,53:crates/hub/src/protocol.rs.