History of Pool::keep 3 changes

In crates/flow/src/cache.rs, lines 207–241 on 33d8ada65f6a48741c7c6e48b00612dd09ce585a0c8affba3c23d99c00536b79. 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 207,241:crates/flow/src/cache.rs.