History of HubBackend::caller 2 changes

In crates/hub/src/protocol.rs, lines 58–77 on 101740454617cd6966001ebd9d7f9f8bc566ca6766325e2f9137f3a9d19220dd. 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 58,77:crates/hub/src/protocol.rs.