History of HubBackend::caller 3 changes

In crates/hub/src/protocol.rs, lines 62–88 on efb51b39db1c38e7b881f05a1ce1c46d09dc3317349df6ebfd24a2c6d12279db. 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.