History of Pool::keep 3 changes

In crates/flow/src/cache.rs, lines 231–265 on 72772aa01d6bcb6907aeeb45b887c82cdfa36a3c63fd6ea4a67c8c1ecc73d5aa. 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 231,265:crates/flow/src/cache.rs.