History of HubBackend::block 2 changes

In crates/hub/src/protocol.rs, lines 51–53 on 745d225de3440f319d14ec371e609ef92a75aebe29802ffd110452153de41a07. 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.