History of HubBackend::caller 3 changes

In crates/hub/src/protocol.rs, lines 62–88 on 75d611ab99d1a8f74e35cfdb963c0c083d16815d921194e980bbfc48aa757fda. 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 62,88:crates/hub/src/protocol.rs.